Earlier quoted context omitted.
This is exactly why I am a huge fan of ember.js Unfortunatelly it fell behind in popularity mostly due to some unimportant reasons (eg not being able to render 1M rows faster than react) and some important ones (load times), but boy did they build a stable ecosystem! I haven't seen such a commitment to stability and guardrail upgrades to this day on any other piece of front end library.
I'm thinking of building a long term living app (say an app that I will use the next 30 years). It has to be a web app so I was thinking of going pure JS. With that requirements in mind would you recommend ember.js?
The fewer things you have in your stack, the fewer things can change under your feet.