High availability and abstraction complexity are orthogonal.

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.

If you want something higher level, there are other systems to reach for.