We already have a thread about this. I tried my best to explain in this post:
And it’s not that people will have to pay to use third party apps. They are completely shutting down on June 30 because Reddit is charging them more than they can afford based on current rates (and forbidding them to run ads).
And, honestly, you’d get a lot more information if you go to Reddit. Check out the /r/modcoord subreddit for more info.