It is a bit of catch-22 IMHO, for some. If you're very experienced it is just as easy to roll your own (although others may not onboard as quickly compared to well known libraries). If you're not very experienced then if you try to roll your own it may wind up being a mess. I'm in the middle and once I understand a library well I know its limitations and use its components as they were intended where I won't have to customize them too much, and roll my own components for the rest. This largely sidesteps the issues I used to have of wrestling with UI frameworks. I hope that helps.
Certainly! I wanted to hear some viewpoints about full vanilla vs framework-based development, and your view of grokking the tools and implementing what it doesn’t cover is a great one to consider.