I have never met an existing ecosystem where building your tools did not make your life easier, at least in the short term. The trick is knowing when to abandon them in favour of a standard solution.

To put this in perspective one team I was on built their own Android NDK, until the normal one caught up.

True, but I've never met an ecosystem where building your own tools is required.

One tool does not necessarily fit all the things. And that would be true of any "ecosystem" that has as many diverse uses as Javascript does.

Versatility is one of Javascript's strengths, not a weakness. And with that versatility you get what seems like too many frameworks.