Cross-platform UIs have been around for ages; QT goes back 30 years. The pattern that Electron and such are continuing is that they do a base set of things wel

Cross-platform UIs have been around for ages; QT goes back 30 years. The pattern that Electron and such are continuing is that they do a base set of things well, but then integrating with OS services is non-existent, even though for any given OS it's relatively trivial. Don't be too impressed that it can run anywhere at acceptable speeds; Java solved that 20 years ago. Rather, it's more fundamental: as you add in all the functionality provided by various OS's you have to model all that functionality and it has to be comprehensible to your users and maintainable by you. Some of that functionality is flatly contradictory and much of it is peculiar to a small audience. You can theoretically engineer around it, but in practice, you won't be able to maintain it and no one will want to use it. That's an intractable problem. That's why I think cross-platform framework authors have consistently been leaving various bits of functionality out for decades. They'd rather deliver "second class" applications than nothing at all, and that's a smart trade-off. But that does leave a lot of space for native apps.