I got the same impression looking for Go a few years ago. I guess in a world without legacy code because it's too new for legacy code, you're going to use the newest programming languages. That was also the kind of startup that was getting funded back then. I haven't paid much attention but maybe the hype has died down over the last few months.
My overall thought is that programming language popularity is a lagging indicator; people might be hiring Java engineers even if they wish they didn't write their codebase in Java. Changing that is risky; getting one more employee can stop the bleeding. Meanwhile newly-formed companies use the newest tools, and thus among newly-formed companies, you're going to see many more requests for engineers with experience with the newer tools. (It's one of those secret advantages for startups; your competitor might be slowed down by all the legacy and thus resources given to your new startup might get more value than if given to the incumbent.)
My overall thought is that programming language popularity is a lagging indicator; people might be hiring Java engineers even if they wish they didn't write their codebase in Java. Changing that is risky; getting one more employee can stop the bleeding. Meanwhile newly-formed companies use the newest tools, and thus among newly-formed companies, you're going to see many more requests for engineers with experience with the newer tools. (It's one of those secret advantages for startups; your competitor might be slowed down by all the legacy and thus resources given to your new startup might get more value than if given to the incumbent.)