I think the main point is that from a human intelligence perspective chess is easy mode. Clearly defined, etc.
Think of politics or general social interactions for actual hard mode problems.
The past decade has seen a huge number of problems widely and confidently believed to be "actual hard mode problems" turn out to be solvable by AI. This makes me skeptical that the problems today's experts think are hard aren't easily solvable too.
Hard problems are those for which the rules aren't defined, or constantly change, or don't exist at all. And no one can even agree on the goals.