Reddit removes years of chat and message archives from users' accounts
mashable.com
mashable.com
They can't be sold for datamining... Why would Reddit waste money keeping them?
My bet is they just sold it for cash.
It seems this action would also have the undesirable side-effect of gradually removing older Reddit pages from search engines.
Plus, data is cheap to store, especially if it’s already stored. It would cost them more to delete the data and repurpose the hard drives.
During summer, when people are on vacation?