I used to agree, but now I'm not so sure. There are huge time savings in having someone already familiar with a specific technology. They've ran across an issue before and can quickly find the solution.

For example, I started learning Elixir a little over a year ago. I struggled with how to get it to change data in place, and the answer is that you don't. You work with data in an immutable way; you make a copy with the change made and throw away the original. Once you get used to it, this works very nicely, and Elixir has quickly become one of my favorite languages. However, few other languages force you to work immutably, and nobody does it voluntarily. It takes a bit to get your head around it, and you'll take a lot longer on any given task until you do.