>Yes. Because mainstream is what you should select for when choosing your tools.

Ease of hiring experienced developers should absolutely be a part of selection criteria, but of course it should not be the only one. What good is it going to do you when you picked Elixir/Scala/Rust over Python/Go/Ruby, you need to hire senior engineers who can hit the ground running ASAP, and you have limited resources/budget?

It's going to be harder to find them (especially if you're not in SF), it's a harder/longer initial learning curve if you hire senior engineers without prior experience, it's going to be harder to find non-seniors, you're going to have to pay more to get what you want...the list goes on.