I don't think so. A/B testing is just not a cure-all and alternative for good design, that is all. I mean, if the pattern is 'don't bother thinking too much about ux, just A/B test everything in PROD to death', then yeah, you are right.
However, there are many products which allow users to enter into a beta or test group, where they are the willing subjects to their experiments (in exchange for the latest shiny new stuff). This has the aspect of consent, leaving the 'stable ring' free of such variability. The fact that google and many startups are not using such consent and offering stability, doesn't mean it can't be done or isn't done.