But it does save time. JS is proof of that. There are no immutable data structures and the world rolls on. People will hate on JS, but it's effective.
You can learn to get into the "immutability mindset" if you train yourself to, but are you certain it's worth the time investment? It seems like there's at least a chance that it's not.
Sure, no arguments there. It does save time in JavaScript and a large part of that is because the language has been designed around mutability.
Part of that trade-off is that JavaScript can't make the same guarantees about what happens when you pass an object into a function. It's harder to be confident that a given program is correct.
Immutability is just a part of the "simple made easy"[1] ethos of Clojure and I think most Clojure programmers will argue that taking the time to understand that philosophy _is_ worth the investment.
Any bad implementation of something is bad. Sounds like immutability in JS is just badly designed and implemented, in a way that makes it difficult and slow to code with.
Don't generalise you're experience of a thing if you've only tried its bad implementations. Like don't judge Monads until you try them in Haskell. Don't judge immutability or DSLs until you try it in Clojure, etc.
You can learn to get into the "immutability mindset" if you train yourself to, but are you certain it's worth the time investment? It seems like there's at least a chance that it's not.