I actually think the problem isn't a glut of designers or UXers, it's an obsession with A/B testing and multi-armed bandit scenarios. I'm sure that at any one time there are dozens of A/B tests running on the site, and the inconsistency we all see is a direct result. Netflix is a similar offender in this area, I never have any idea where "continue watching" is going to be when I open up the app.