GMail won because I had to keep deleting email from my old provider, Google was pretending to "not be evil", and they offered me an ever-increasing amount of storage. Then I told my friends about it. Eventually, everyone used it because everyone who should've known better (myself included) recommended it to them.
Not everyone recommended it to the masses. Some cautioned against it from the get-go - and Google was a problematic company with too much power already when GMail was being rolled out.
I don't doubt that Google pre IPO probably believed in their motto. It's the investor influence that has gradually steered Google into lucrative but ethically questionable domains.
