This doesn't mean very much. Most people find the Rust borrow checker "vaguely confusing" (if not very confusing), and most people also wouldn't use it were it not strongly suggested by both the compiler and the community ("suggested" as unsafe Rust exists, but you of all people are aware of that).

Conversely, I understand condition systems, and I'm not a very good programmer. (I've tried and failed to learn Rust once already) That's a pretty low upper bound on how hard they are, especially relative to advanced features of languages like Haskell.

We're very fortunate that programming language design doesn't advance solely by giving people more of what they already use.