Not complete true. You get a gmail email address when you create a Google account, but you can add an alternate email address as well. Later, if you decide, you can cancel your gmail account while keeping access to your Google account using your alternate email (now primary) as your Google login username. Actually, you can use your alternate email as your Google login username even if you don't cancel the gmail account that comes bundled with your Google account.
https://support.google.com/accounts/answer/1728595?hl=en
In addition, those of us who host our own domains (or at least the email portion of it) on Google Apps do not need a gmail address. I have no gmail address associated with my main Google Apps account, nor has there ever been one associated with it...and that's what I use as my account on Android. Of course, the email portion of Google Apps is essentially gmail for your domain.