I've done my best to research this and I'm unable to find any numbers on the matter besides one app developers miscalculation of 20 mio. for billions of requests.

I can however find official documentation that backs up what the admins are saying. The new Data API terms says they no long allow commercial use of their APIs and might implement a cost pr. request. It links to the Data API docs that says 60 req. pr. minute are free as long as it is non-commercial. I would think unofficial reddit apps goes under the non-commercial clause.

To me it looks to be a complete overreaction by the Reddit community because of a miscommunication on parts of a single developer and the Reddit orgs too slow reaction to stop it from spreading.