yeah, I bet if you talked to the average front-end dev and told them they spend all their time writing poorly-implemented lisp, they've have a few choice words to say about it ;)
From the CS point of view, sure, there are only a half-dozen languages. From the IT point of view, having a few years of experience dealing with the exact details of the "poor implementation of lisp" makes a massive difference in productivity and effectiveness.
There are also widely separate concerns between front-end and back-end. UI patterns is a whole discipline in itself. Deployment and CI, AWS vs DO, not to mention containers and swarms, is just a subset of one aspect of "dev ops" these days. There's also the entire subject of database design, of securing HTTP/S/2 traffic, data encryption schemes, logging strategies. It's endless, on both sides. And none of the skills are transferable. Knowing AWS doesn't help you implement a UI, and knowing React does nothing to help you design a database.
I dare you to try implementing a complex UI in React after learning FP, reading the docs and a "few days" ;)
But to get back to the analogy... I can easily see a neurosurgeon saying "teeth, they're just specialised bones! Give me a few days to brush up on the basics, and I'll have that wisdom tooth out in a jiffy" in the same manner.