It's mostly collaboration-related: I work in several projects with other people. What I have built for my project might indeed be better than React for that par

It's mostly collaboration-related: I work in several projects with other people. What I have built for my project might indeed be better than React for that particular set of needs, but I'm much more likely to find people who know React (or any other popular framework, React's just an example here) and start working with them, which would be impossible with my custom framework. Actually exactly this happened: even though my code was super-clean (for me, at least) it took me days to show how it worked to a collaborator. In the end he gave up because no matter how I explained him, he wasn't learning it, he was memorizing it (maybe my fault for not being clear, maybe his fault for not focusing enough to understand), and we gave up and because of business constraints I let him go his way, messing up the whole project with spaghetti code. On the other hand I joined a React Native team, and day #1 I was productive, writing actual working code, because we spoke the same language: after a brief one-hour intro to the project by the people who wrote it, I knew the hierarchy, how reducers and actions were organized, queries were dispatched etc. I hear you, and what you do is actually what I personally love doing too. Sometimes I try to reinvent the wheel and that's not necessarily bad: it teaches me A LOT about why some frameworks/libraries are the way they are (just like my own code before I knew about React and how the idea was similar) but if I'm going to collaborate with others I'd still use React or whatever suits as the common denominator of all devs for the sake of throughput and maintainability. It's not that I don't trust my code, it's more that I just have trouble teaching it (or lose a lot of time doing it while I have tight deadline constraints).