Yes there are more apps using ActiveSync than using EWS.
Does that make EWS not valid at all? I don't know!
But it is a standard, official, documented, support Exchange feature.
It's been there in Exchange since November 2007 and it is enabled in Office 365 and most corporate installs too.
Some IT people do turn it off, for security reasons I guess.
But then those same IT people could lock down their server so it's only accessible from Gmail app, the iPhone app, and the Outlook app (for example) and not from *any* other mobile mail app -- if they wanted to. And then I'd not be able to work around that either.
And so it all boils down to administrative not technical.