The challenges mentioned on the article are challenges that are known to every larger distributed system. They are not challenges solved or to be solved by functional programming.

But the solutions and tools functional programming provides help to have higher verifiability, fewer side effects and more compile-time checks of code in the deployment unit. That other challenges exists is fully correct. But without a functional approach, you have these challenges plus all others.

So while FP is not a one-size-fits-all solution to distributed systems challenges, it does help solve a subset of the challenges on a single system level.