> If an app depended on remote authorization, why wouldn't it simply disable itself after a grace period?

Because some people still use computers without internet connections – especially users of “pro” applications (widely defined, e.g. anything made by Adobe), which are some of the most commonly pirated applications. I can confirm from experience that cracks telling you to prevent the program from connecting to the Internet are a thing.

My first thought was that that flow could have the potential to produce false positives, such as from spotty internet connections. This might lead to a poorer user experience, similar to how some legitimate purchasers have had with certain DRM laden games.