Spurred. Firstly, this ignores the variance between absolute decentralization and absolute centralization. By reducing the discussion to black and white, we can't recognize a middleground that may not be as decentralized as all-in-home yet not so centralized as owned by a few. I'd argue that much of the internet remains in this middleground, popularity notwithstanding. Secondly, what is and isn't mainstream is the result of ease of use, implementation quality, and improvements over alternatives. Popularity and other knock-on effects may follow, but needn't be the initial goals. That these aren't achieved in decentralized setups is not evidence that they never will. When they are, and the economic forces then come along with adoption (that's the usual order after all), you'll see a shift in focus without necessarily a shift towards centralization. Until then we accept that centralized versions of more popular services are better implemented currently.
One thing everyone agrees on, the vast majority of users don't care (nor should they).