I don't think that's true. Can't speak for everybody but for the stuff I worked on. Quorum reads at RF=3 are only twice as slow as reading a single node and it's pretty practical, if you care about it, to write and read using quorum writes/reads. It's true there's many applications where you're ok with some time not reading your latest data, and for those you can get somewhere better performance/latency for a given scale by going CL=ONE...