> The MVC idea of separation of concerns on the surface seems like a good idea, but the reality is that I've never been on a team that was disciplined enough to actually keep things separated.

on the native app side, ive seen this too with mvc, mvvm, mpv apps: people just arent very good at deciding what goes where in many specific cases

im not sure, but my guess is, the more layers you have to maintain, the higher the cognitive load that one has to implement so many parts, they start to tire and without knowing it, smear things across layers, making a huge mess over time