If the average usage of the service is 5GB, then the 70+ TB users are a rounding error in the statistics and not cause for panic. With the number of users OneDrive is supposed to have, the few users who are uploading vast quantities of data will be lost in the sea of small updates by millions of people. If you can't handle a dozen heavy users of your service, you haven't a snowballs' proverbial of handling millions of concurrent connections.
I think that the heavy users were brought up as a smokescreen to generate understanding in favor of Microsoft. Why the timing of this eludes me, but it is far less important than the all the justified backlash going on. The marketroid who thought this up is going to have a hard time pitching for a salary raise come December.
Oh well, just another bullet in the foot for Microsoft. Foot must be made of lead by now.