I don't think this is really surprising. I don't know a ton about distributed systems, but the last time I read up on formalizing them and proving properties it seemed like an incredibly daunting task. There's an exponential blowup problem in that you end up having to follow every state in the state spaces of every actor against every other state over time. I saw some interesting proofs which used topological invariants to keep a hold of that whole complex more delicately... but to actually just dive in and try exhausting it cannot be simple.