I've been using Google for many years and never had this happen.

I'm not sure what you mean by a different account for each service removes the benefits. At this point all of the services I use are under one account - my main email address. They are all nicely integrated.

My only complaint is that I can't alias all of my other email addresses off the main one, having a "single Google identity". So - if someone else uses one of my other email addresses to share a doc with me, I have to either logout/login or re-request the share using the doc I want (which is the path I use).