for simple feature 3 frameworks and 3MBs used, developers are not thinking, just copy pasting...
I think you nailed it right there. The problem isn't the ecosystem, it partially does contribute, but it is largely the inability to understand what to use for what problem. To be fair it's a hard decision to make usually, even experienced engineers get it wrong OFTEN. Most frameworks and tools are great at solving specific problems and once you face that problem those tools are a godsend. The problem I see is people try to overcomplicate things and use these tools where they aren't really needed (says a guy who wrote a personal site in react :/)
Another reason for the craziness is that you're working with a single language for the whole internet population. In the backend world there are a dozen of languages, each of which has gone through the same problems at a slower rate, smaller audience. With frontend there is one, and a few years ago everyone suddenly started caring about it, so you got 10+ years of innovation over a dozen languages/ecosystems packed into 3, of course it'll get crazy.
Contrary to what a lot of people feel it's a good thing. Innovation drives progress forward and propels new ideas into the open. To keep sane just stick to a few frameworks/tools you may need and know them on a high level, if you have a project that would benefit from one them learn them deeply. If you have a project that doesn't feel right with the ones you know, look for a new one or write one that solves that problem
It is impossible to learn everything, just learn enough to make yourself be effective at getting the project done