I think its kind of disingenuous to make such statements. If you see how google is still unable to move from python2 to python3 we will know its a technical problem [1]. And remember chromium is a project with huge number of employee paid with very high amount of renumeration. So the barrier is mostly technical. I think such attitude comes from frustration which gets complemented with time.

I personally think python3, ruby etc. are way better than JS in many case but I think world is a bit unfair due to browser language monopoly here.

1. https://bugs.chromium.org/p/chromium/issues/detail?id=942720