One would think that if Office de-activates itself, there would be some sort of event logged for this. One would also think that it would be on record that the same computer has been activated on the same account multiple times and that these events would be readily available to anyone who bothers to look. One would then also hope that the tech support people would use this information to find the true cause of the issue. But I guess that is too much to ask for.
As a dev who has spent a lot of time root causing and fixing bugs, uninstalling and re-installing seems unlikely to fix the problem. Instead the tech support person is copping out and letting me do all the work by uninstalling and reinstalling, and hoping that when I call back next time to report that it didn't fix the problem, I'll probably not be talking to him but to someone else, so his problem is solved.
Also, do you consider having to factory reset your phone to be an acceptable workaround when losing WiFi after a WP update? I'm asking because it was that, combined with this Office 365 issue and its proposed "solution" that really ticked me off.