Sure the A7R2 is not a sports camera...but that is such a small niche pro photography market. The A7R2 is very capable of shooting weddings, portraits, events, landscapes, travel etc...
Remember when the 5d2 came out...it was heralded by the wedding crowd as such a great camera...the A7R2 focus system is much better and more advanced than the 5d2...yet you say it is not capable of shooting weddings...not true at all.
Yet most Canon-shooting wedding photographers continued to use the 1D3 or 1Ds3, or combined the 1D3 with the 5D2 for great image quality in the posed stills as well as AF which could actually focus on moving subjects during a dimly-lit ceremony. And the Nikon shooters used the D700, which had the same AF system and sensor as the D3. The wedding photographers who moved entirely to the 5D2 seemed to be the ones shooting more posed/static shots and fewer action shots, as well as those who shot a lot of video, emphasising the video part in their combined photo/video wedding packages. Most notably, a lot of the ones still shooting the 1D3/1D4 moved to the 5D3 when it came out, since it corrected a lot of the deficiencies of the 5D2 which made it less than usable for even slow-moving subjects in low light.
Notably, these seem to be the same types of wedding photographers who moved to the A7r2 and A7s2 - particularly the early adopters, who made the move before the GM lenses became available. Most of them seemed to be video-centric, often lower-end photographers offering budget packages. You didn't see too many high-end wedding and event photographers moving to Sony (the A9 is different and has attracted a much wider clientele) - there were far too many deficiencies in the system at that point to ditch the SLRs just yet. I would expect sizeable number to start shifting to the A7r3 over the coming year, since it corrects almost all the deficiencies of the A7r2, in the same way that the 5D3 did for the 5D2.
Also, the 24-70 and 70-200 f/2.8 lenses weren't available until the middle of 2016. Those are probably the staple lenses of wedding photographers (with 35mm and 85mm f/1.2 or f/1.4 primes being the usual secondary lenses for nonmoving/posed shots). What were your A7r2-using wedding photographers shooting with before that?
You seem to equate shooting sports as the only professional market...but in reality it is a very small market that will get eaten up by stills being extracted from video in the next 5 years.
My feeling is you are listening to a biased crowd rather than having your own hands on experience.
You know you're probably on the right track when mirrorless users attack you for an SLR bias, while SLR shills repeatedly attack you for a perceived Sony/mirrorless bias. You've pretty much quoted me word-by-word from numerous other threads, where I've said that professional photography is much more than just sports.
But action is much more than just sports. Any time you're shooting something that's moving and need to track a moving subject, you're shooting action. A walking person in dim lighting during an indoor event can be just as difficult for an AF system as a running athlete or fast-moving race car - the lighting is worse, the distance is closer (meaning bigger moves in the focal plane) and the accuracy required is often greater (focusing on just one part of the body, rather than the athlete as a whole). Also, the stakes are often higher - a footballer will kick a ball many times during a match, and it usually doesn't matter if you miss one particular kick (and, on the occasions where it does, the action is often stopped and you have time to pre-focus and pre-compose on a known location), but no-one is going to walk down the aisle more than once per ceremony. The A7r2 can reliably and accurately lock focus onto a subject (the original A7r couldn't even do that in low light), but doesn't do a great job at tracking it under less-than-ideal lighting or at high speeds. You could trust it to focus accurately for the nonmoving parts of an event (e.g. presentations on stage, or photos at a cocktail party) but not to track it quickly or accurately enough after it acquired initial focus - particularly when the thing you needed to track wasn't a visible human face. Even a one-in-four chance that you'd end up with a long sequence of slightly out-of-focus images of a walking person isn't acceptable when you can't repeat or re-stage the shoot.
And pro photography requires much more than just a reliable AF system. Even discounting the lens ecosystem (which didn't meet the requirements of most professional use outside of nonmoving subjects until mid-2016), you still need dual card slots, good battery life, rapid start-up time and, in some cases, reliable tethering (notably, many of the applications which don't call for fast AF require good tethering). The A7r2 had none of these things. There's a reason the only action photographers (to use the broader sense of the term) who moved to the A7r2 were low-end photographers offering budget packages for parties, weddings and other events, as well as the video-centric ones who also used the A7s2 - most of its pro users shot things that didn't move much, while pro action shooters stuck with their SLRs. Losing a wedding due to card failure can be a business-destroying disaster.
I've been saying a similar thing about video and action photography since 4k came out. Once 8k comes out (definitely before July 2020), video cameras will also be 39MP/25fps mirrorless cameras, with full AF capabilities. You won't be extracting stills from video (since video might be shot at 1/30s exposure, while shooting for stills will require 1/500 or faster) but will be shooting both with the same camera and lenses, with different settings depending on whether you're trying to shoot stills or video.
Basically, mirrorless technology is rapidly evolving and not yet mature. The A7r was essentially a sensor-in-a-box, a proof-of-concept prototype - very good for what it did, but also very limited in application (lack of EFCS being its greatest weakness in its roles). The A7r2 was much better, but no equal to the SLRs of the time - apart from resolution/DR (which are sensor qualities rather than general camera qualities) it could not outshoot the 5D3 or D750, which were several years old by the time the A7r2 was released. It was akin to a 5D2 released in 2015, with an updated sensor, but with other parts hanging around 6 years behind the times - better than the 5D2, but not up to the capabilities of the 5D3 or D750. The A9 and A7r3 change everything - they are really the first mirrorless cameras able to compete against their SLR contemporaries on an even footing, in all areas of photography. Better in some respects, not as good in others, but overall equal to the D5 and 1Dx2 (for the A9) or D850 (for the A7r3). It is not a mature technology yet, but evolving much faster than SLRs (which have almost reached their technical limits), and there's little doubt that either the next generation, or the one after that, will exceed SLRs in capability.