Multi-DPI is kind of a hack in general though and is likely to cause issues unless applications have been tested for it very thoroughly, it causes serious issues on major frameworks like Electron and Qt - though both of their support for it is improving slowly. If you want things to work smoothly for now, try to stick to 1 DPI setting.
It's not windows fault the apps don't take advantage of DPI.
You can also disable dpi scaling for individual apps.
It's "not Windows fault", sure but it certainly makes it a worse experience than other platforms like OSX where multi-DPI is much more commonly supported.
I mean, I get it, same issue as Vista for Microsoft - people expect 100% backwards compatibility, but it turns out that terrible design decisions made many years ago tend to mean you need to break compatibility. Just like UAC, resolution scaling will be an issue that becomes less painful in Windows over time. Right now it's not great, however.
Just most apps chose to ignore it, the developers took the 'anyone uses 96 dpi anyway' attitude and at the end of 90's most applications started to suck at 120 dpi.
I guess people got lazy, as you say.
No point in spending time on logical pixels if it makes almost no relevant difference...
If you're making a decision about whether to make a purchase, don't make it unless you're prepared to do it all at once. Stick to ~100 DPI until you can make a commitment to go all at once.