Oh, it's super hard to build good interfaces, I'd never claim otherwise. Everything user facing I build is trash and I know it, so I work with UI people. I would assert that most of what's made under the banner of "UX" by people who think they're good is also trash from a usability perspective.

(it's possible that the ux people are optimizing for something other than end users getting their stuff done, like conversion rate. But that doesn't make a trash interface good, it just means you get to pay your mortgage this month.)