24" 1080p is hardly tiny, man. It may not be the latest and greatest, but c'mon...
https://gs.statcounter.com/screen-resol ... 201909-bar
1080 is still the most common monitor size. Lets assume 'other' are all >1080p, it is less than half of the top two combined (1080 + 768). Undoubtedly this will change in time, and i will upgrade at some point, but for some (inc me) upgrades are something I need to save for (because disposable income, etc).
And while musicians are probably more likely to be on the cutting edge, I suspect a good percentage of KVR'ers are hobbists, bedroom producers, etc., who are not leading the charge to 4k.
The problem looking in the other direction is that a *lot* of VST don't offer scalable gfx yet and >1080 they are pretty much unusable.
Rock meet hard place.