Hello Eric,
I agree with all the points you made about the necessity of tripods for very long exposures and I also understand that some people really enjoy the slower, contemplative approach that a tripod can offer you, even in good light conditions. I shot landscape 4x5 for 30+ years and also enjoyed that difference from the handheld 35mm film camera shooting I did back then. And I agree that Macro can be easier and give more predictable results IF (and that's a big IF) it is practical to use a tripod. And I agree that huge, heavy, long, big aperture lenses require a tripod or monopod to keep from breaking your back in addition to eliminating motion blur.
But I differ with you on one account and several other statements made by others in this thread that paint the SHARPNESS benefits and the resultant "quality" of tripod photography TOO BROADLY. I think your statement that ...."For the absolute best image quality, if you can use a tripod, you should..." is too all-encompassing. Based on the test I did, I'd revise your statement to be something like.... "for the absolute best image quality based on no visible motion blur with my 12-40 zoom, I should use a tripod whenever my shutter speed, using IBIS will be less than 1/30th." Another statement in this thread that was obviously too broad was this one....."if you're putting serious effort into your landscape photography, you're interacting with the tripod and head on every single shot" Huh!!??
And I also was making the point that in my opinion, given your specific body and lens, you only need the least heavy/expensive tripod and head that will eliminate motion blur on "long" exposures for that camera/lens combo. You don't benefit any further from added weight or cost.
My post was made because I thought that overly broad, sweeping statements were being made about big, heavy, expensive tripods and heads. That was the purpose of my post.