I'm not really sure what you mean by "constantly impending obsolescence", but as one anecdote in the face of that: I have plenty of core JS code in production that was written 3-4 years ago. I've gradually improved or changed parts of this codebase but that had absolutely nothing to do with external libraries of which I use very few... this feels very unchanging to me, my code is not about to implode due to any external reasons.

I write my own UI/MVC type code from scratch just because that's the way I roll and my requirements there are a combination of minimal, extremely performance sensitive and in many cases esoteric where I have to write the UI anway so it's not much work compared to forcing existing libraries to do what i want... but if had to I could replace it with some hip and upcoming UI + MVC library and still keep 95% of my core code completely independent and intact.

I think JS world feels like massive churn if 90% of what you are doing is UI UX etc, because that's the interface that can never sit still in the name of progress... either that or you (not you necessarily) are doing it wrong and not separating UI code from your application code (I've seen this happen quite a bit in ye olden angular days where everything becomes attached to angular for no apparent reason, and angular itself is the worst of OOP + MVC where everything is convoluted and difficult to follow).