Most languages in use today were developed for different purposes than what they are primarily used for today. That's a non argument unless it has significantly worse time dealing with it's past than it's competition which is debatable, but definitely not objectively true.

Everything else means, you have to learn two different languages with two different syntaxes. sets of quirks and exceptions, that you have to maintain two different codebases that cannot share any code (like types for instance) (specific exceptions aside), you cannot have type safe data from http requests, you can't leverage the largest and simultaneously fastest growing ecosystem of today...

I am not saying js (ts) is always the best choice, just that sometimes it actually is.