Because the majority of people enjoy it? And the common user wants fast load and doesn't care about the philosophy of data retention and web ownership?
Reddit links via Google search results were broken for months on my iPhone because of AMP. How many other users had the same issue and no idea what was going on?
That's reddit's fault and isn't anything inherently wrong with AMP itself. Just because someone uses the technology wrong doesn't mean we should hate on the technology. If I use AngularJS to make a Neo Nazi site, should we all boycott that library?