The creation of hypothesis is often glossed over as a trivial first step in scientific or data-driven decision making, but in fact, that's where the magic lives.
Nice strawman. I have never said to never talk to your users, but to pretend that using data is meaningless and you should follow some bullshit and vague "good argument" instead is just sheer foolishness.
When you've got an early product, there are probably things you can do that 2x as many people will like as dislike. Even a small set of customers will be good for discovering this. When you've got a mature product, you should be optimizing around the edges and need a large sample size to find those 1% wins.
Likewise if you don't have scale, there are a lot of well-known best practices that probably improve your site by 5-10%. You probably don't have sufficient volume to discover test those ideas, so following general best practices is a good idea. But if you have scale, you can and should A/B test the heck out of everything. And then do it again in a couple of years in case the answer changes.
Of course you need to interpret it but its incredibly important and I do not think you really know what you are talking about.
https://www.ycombinator.com/library/6g-how-to-talk-to-users
Almost all the major fails I have seen in my career have been some derivative of not understanding your users.