[xp84]

It makes sense though -- Gmail has little in common with normal email besides usage of SMTP transport, and has a lot bigger market share than normal email. (Exchange also doesn't count as "normal email" - so that's the reason for my confident assertion.)

[ljm]

I don’t think it makes sense, per se, considering Gmail’s ubiquity comes from Google offering it as a free product, and then all the barriers to creating an email provider being raised in an attempt to combat spam.

There’s barely any point in setting up your own provider now because you have to compete both with free. All the action has been around email clients which have typically been acquired and then crushed.

Google could have stuck with the protocol or presented a spec for it, rather than leaving the competition with IMAP and SMTP.

What makes sense is they dominated the market and helped put up roadblocks afterwards. EEE.