React is a lot more stable than I think you're giving it credit for.
> And the stability also means that more time is spent on delivering features
Frameworks/libs also exist to save you time, thus letting you spend more time on delivering features. And fwiw, the obsidian team seems to agree in principle. Your link goes to a forum post of some kind, in which one may find a link to obsidian's third party deps: https://help.obsidian.md/credits#Third+party+acknowledgement...
These do not include React, but do include:
- i18next - lezer - moment.js
Plus a bunch of others. Why didn't obsidian write their own date lib and chose to use moment.js? Because it saved them time, despite the fact that moment.js does make changes, and many people are moving on from it in any case.
The idea that not using a frontend framework will let you focus on delivering features seems reductive, and the obsidian anecdote doesn't support the idea anyway.
Whatever you're building, it's never a bad idea to deeply understand the tradeoffs that using a library will bring. Obsidian probably couldn't accept the downsides of React due to them needing a bunch of custom renderers for content, which React makes harder. But that is likely a rare constraint for apps in general.
Generally speaking, libs like react exist to save you time and help you focus on delivering features.