A high availability protocol should not leak into the client. It should be able to discover other nodes. It should not land in broken states so easily. It should not limit the number of writers. It should not error during failover.
Are these hard problems? Yes. Should we just accept that things are hard because that’s how the gods have given them to us? No.
Redis is a low-level concurrency primitive, and it made certain choices in dealing with CAP.
It might be single-threaded, but it can easily absorb 100,000+ requests per second.
I've built systems that handle billions of dollars of online payments flow, active-active, with six nines of uptime reliability on top of Redis. It does what it says on the tin, and it doesn't need to be everything for everybody. This is a hard domain and you're going to have to deal with different problems and tradeoffs.
If you want something higher level, there are other systems to reach for.