The main issue is that people mix conversion with customer obsession! Whenever you work on a product or feature you should be asking yourself "Is this really good for my customer" - if the answer is no, then no matter what the A/B tests/conversion rates show you don't do it.
Unfortunately we mostly hire the wrong people as PMs, who then hire clones of themselves. They are not truly customer obsessed and use A/B tests incorrectly which results in products that trick or force customers to do things they don't understand/want to do. Long term this is bad for the product and company