Evidence would suggest otherwise. I can build a decent and reliable frontend with a no code solution. That's not to say frontend is "easy", just that trying to say which is harder is ridiculous. They're different.
I personally don't like working on frontends because it feels like getting on a hamster wheel that spins faster than in any other domain. ymmv though.
If a user enters a number incorrectly on a frontend, a frontend can’t just say no. It might have to try its best to parse the number, or if it can’t, the error has to be presented in a user friendly way. A frontend can’t just throw an exception and say Bad Request.
Followed by the distant sound of enterprise, banking, and government frontend devs laughing.
A system can't just reject data it doesn't like.
Things that can be built that way are not interesting. Of course you can just assemble online stores without writing a single line of code, but that's not exactly programming. We are talking about frontends that have some sort of novelty or at least non-standard flows in them.