I’m not sure this data’s worth a lot though, as many users (likely most of them) are using anon or throwaway accounts with none to little link to the rest of their activity. Sure it can be processed for statistics but I don’t think there’s a lot to extract further. Reddit is no facebook where the average joe has its “average joe” account, and I don’t think signing up with a google/apple/whatever account is the most common practice on reddit (or at least with your real, non-portmanteau anon account).

As for archived posts and comments they’re already publicly available on archive sites. Why would anyone buy them?