[risyachka]

All in one (Mobile, desktop, web) always sounds nice until you actually do a multi platform app.

Then in 99% of cases you find out that those 3 have very few things on common. UI usually has to be completely re-designed for each platform, each has unique features that are not and will not be available on another platform etc.

You'll need to have a shit load if "if os=='desktop'" or even more granular like 'android' etc.

And if your app it not tiny - its just simpler to redo UI in a proper specialised framework.

Nowadays it is literally a very simple issue as existing frameworks are very mature.