Startup time isn't what is holding the language back. In my opinion it's: 1. Tooling. You end up spending way more time getting your tooling setup than it should be. 2. Difficulty in learning. 3. Clear best practices and frameworks. The philosophy of composing libraries is extremely powerful, but to gain broader adoption you still need straight forward frameworks and opinionated best practices. The last point has man…
I think you are omitting the main reason why Clojure never succeeded: it's dynamically typed at the core. It's on the wrong side of history in that respect. I know it's trying very hard to catch up to statically typed languages now by retrofitting some type system, but it's too little, too late. Static types are where the current state of the art is, and we're not going back. Clojure missed that train and will never…
I think dynamic languages are generally a good default, but the current world also matches them pretty well because programs talk to the outside world in a lot more varied ways than before and static typing is not that very good across distributed systems.
Static has a better case when talking about more powerful type systems than what mainstream languages have, but those don't really show accelerating signs of breaking through to mainstream. Rust is an exception in the recent history but it's not really poised to become a widely applicable app programming language.