This sounds like at least one rationale for an anti-trust case.
It'd be splendid if antitrust cases happened more often, Google must be due a dozen at least.
Also: Gmail's spam filters are one especially egregious abuse of power. Email is another technology Google hates and which deserves to survive without Google hamstringing it
Microsoft isn't better in this regard though: they don't have an "allow all" filter possibility, and will delete spam emails after two weeks. I've gotten invoices, personal email, and job offers deleted this way.