If you're telling me that anyone can be as good as someone else who is equally smart but with 2-3 years of experience with that specific tech stack, I'd say that can't be true, almost by definition.
Have to agree with you there. I started a job using the exact same stack I was using in a hobby project. I had my dev environment fully up in less than two hours and had production ready PRs by noon. On my first day. Then someone got it in their head to rewrite everything in react (2014) and we slowed to an absolute crawl. We never saw the momentum we had pre-react, at least before I moved on two years later.
I'm not so sure. I'm saying they can be efficient with it.
More efficient than a jr with 1-2 experience in it for example. ( If the implementer that is new knows multiple languages and there isn't a fundamental big difference ( eg. the new language is functional))
If you're telling me that anyone can be as good as someone else who is equally smart but with 2-3 years of experience with that specific tech stack, I'd say that can't be true, almost by definition.