Yeah, people pointed out when Ripple launched that there was no reason to believe its consensus algorithm would reliably reach consensus, and the developers dismissed their concerns. I think someone even demonstrated that certain network topologies would result in a permanent fork in the transaction history, and they dismissed that too.

(Stellar was, of course, founded by a couple of the Ripple founders using exactly the same technology they used for Ripple. Also, we're talking about the new "decentralized" Ripple here; there was an older version of Ripple that was centralized but didn't have the same problem, and that's the version that predated Bitcoin.)