So why is Microsoft making these changes? It seems because a small number of users were backing up numerous PCs and stored entire movie collections and DVR recordings on OneDrive. In some instances, this exceeded 75TB per use, which Microsoft claims is 14,000 times the average.
Since we started to roll out unlimited cloud storage to Office 365 consumer subscribers, a small number of users backed up numerous PCs and stored entire movie collections and DVR recordings. In some instances, this exceeded 75 TB per user or 14,000 times the average.Customers that exceed the new quotas will have access to their files for at least 12 more months.
Source: Windows Central