Unless you spend all your time writing, sending, receiving, and reading email all by your lonesome, we're primarily thinking of the individuals, organizations,

Unless you spend all your time writing, sending, receiving, and reading email all by your lonesome, we're primarily thinking of the individuals, organizations, and businesses which correspond with you. None of your friends or family use Gmail? You don't know anyone in school or college who's served 100% by Google Workspace? What about businesses? You probably don't even know which businesses use Workspace and Gmail, because they're using their own domains. Google has a significant corporate buy-in, so if you take away Google, then you're left with Microsoft for businesses, which is still surely the biggest player, but Google is second, because Apple has no comparable offerings in this regard.