I'd also argue that a lot of the complexity in web standards is also Google's doing to prevent Chrome competitors from popping up.
* Web mail client
* IMAP/POP3 services
* MTA (RFC 821/822 and later) core email services
* Security services and SPAM blocker
* and there is more that I am just not thinking about right now.
Each of these things require their own reverse proxy support and they have to talk to each other like they are neighbors and on and on