Earlier quoted context omitted.
How is this possible? How is consul not self—healing? It just seems so brittle in a way even database clusters aren’t.
All distributed decentralized systems are brittle. The only people who don't think this are people who haven't run them at scale. Also, "self-healing" isn't really one thing. There are hundreds of different problems that can take out such a cluster, and every single one of them needs its own "self-healing" mechanism. These systems are literally the most complicated kinds of systems.
"Should have self healing" can be expanded into "should have systems to address the underlying system failure modes", which starts to shed some light into why distributed systems will always run into failure modes.