I would call it more of an ecosystem mishap that carried forward too far due to the sometimes-uncontrollable nature of human masses.
This is why politics are so sketchy. Imagine if in January all those people actually broke into U.S. congress. It could have happened, and it could have ended with dead politicians, and all of it sort of randomly at that. People "blamed" Trump although maybe he didn't actually order it.
To this same effect. I'm sure parts of the language have carried on because things were there, and people simply continued to use them. This happens a LOT. I see it all the time in code bases. People copy a pattern without thinking of a different solution, just to get things done.
I would highly consider the chance that JavaScript's mistakes can easily be attributed to this random human phenomenon.
How can it be improved? Perhaps by making a better consensus system. At the moment, there are a very few amount of people in TC39 that, in my opinion, are not valuing developer experience as highly as we could.