Until recently, Reddit did not have an OAuth2 authentication library that was compatible with the other services we provide. They updated that sometime recently (not sure when we last looked, but it's available now...).
We agree Reddit is a huge community and we'd like to add them. We'll be investigating more and let you know what we find. *Usually* adding a new provider for basic authentication is a pretty straightforward task and I could see it being in a future update (over the coming months.. not weeks.. not years)..
Additional features like reading posts the user may have made (if even possible) is a a more custom process.. so I can't guarantee what additional integration we would be able to support.
I hope that helps answer your questions, but if you need anything else, please let us know!
Great to hear that Reddit is on your radar now. For the site I'm developing additional integration is not required, just authentication and login.
I look forward to a release when it comes.