And yes, tracking what users focus on is very relevant to building a good product. But that kind of entrepreneurial mindset is largely absent in Europe - my guess is most Europeans with such a mindset eventually go to America, whether they were born in 1850 or 1985.
So not tracking every single molecule of detail about your users is incompatible with building a good product?
If being entrepreneurial means that I have to violate my user's privacy then I'd rather not be an entrepreneur, thanks. And again, if your business can't survive without being invasive and malicious to your users, then your business shouldn't exist. You won't see me or anyone else reasonable weeping about the dissolution of such entities, either.
If GDPR was really that problematic then it would be all over the news instead of a few nationalists outside of EU arguing about hypotheticals on random message boards.
GDPR doesnt prohibit you from monitoring your product. It just gets very serious when you abuse users without them agreeing.
Like Threads not launching in EU because of that.