But collecting data and looking for insights doesn't mean you mechanically optimize features, especially user-hostile ones? This is just as, if not more, likely to happen when basing your decisions on what people say they want over what they actually do.

If we were perfectly rational, then yeah, more data should never lead to worse decisions. However, it's easy to fall into the trap where being data-driven makes you only work on those things that you know how to measure.