What is the point of subscribing to a thread?

In the upper right of the page, next to the PMs button, there's a Subs button. All threads you have subscribed to will be listed there, listed in order of most recent activity. Essentially, it's an easy way to keep track of threads you care about. Rather than having to go into a roleplay section and look for your thread amongst others you don't care about, you can just click the Subs button and have it right there.

Revans Exile said
What is the point of subscribing to a thread?

Basically required for keeping track of your topics in Spam or non-Advanced RP sections.