A/B testing does not inherently lead you to good design. If you A/B test what people want based on their revealed user preference, you get gambling apps and doomscrolling.

It has become very clear over the past decade or so that you cannot make truly good software just going off A/B testing. It leads to something which is tolerable to everyone, but not actually good for anyone, and which taps into the self-destructive impulses of your users (doomscrolling, etc).

All of the pizza chains from my youth A/B tested their ingredients into a weird hill climbing problem. They are all worse tasting and more expensive but despite tasting very differently they are basically equal in how good they taste. You can't really say one is better than the other but they are definitely all worse than they were before.