Nothing about GMail's dominance is related to centralization. Everyone moved to Google because they offered (I think) a full gigabyte instead of the mere megab

Nothing about GMail's dominance is related to centralization. Everyone moved to Google because they offered (I think) a full gigabyte instead of the mere megabytes that was standard at the time. And it also had a really slick web interface that didn't require setting up software. People could finally use it for work, or to send pictures without managing space or an email client. "Never delete anything" was the big selling point. Every mail host has a web interface now and provides lots of space, but it took too long. Inertia keeps GMail dominant, not centralization.