... Both Photoshop AND Lightroom's gamut warnings are not accurate! All you have to do is take an sRGB image into LR, load sRGB and ask to see a gamut overlay. There should be none. But there is some overlay depending on the image. Adobe knows about this tiny disconnect and I don't think they'll do anything to fix it (cause the gamut overlay is kind of worthless anyway). Well it is kind of useful to see what OOG colors are in the image that fall outside display gamut. At least you get some idea on your sRGB display what you're not seeing!...
Just how useful is that
As for your other points, several of us posted how we find the Print Size feature useful, none of which included judging sharpness, yet you keep repeating that straw-man argument. It is certainly not an earth-shattering feature of PS, but it can come handy. It was there for as long as I remember Photoshop, thus not something that a "few weirdos" are asking to be added.
Anyone "educated enough" to use Photoshop, is certainly educated enough to figure out their screen PPI. If not, head over to Google, type "screen ppi" in the search field, and the second top result would be "List of displays by pixel density." Find your model and voilà
! Remember, that needs to be entered only once, into Photoshop Preferences. That those preferences are now considered by some as "obscure" is... well, a surprise, to say the least.