There are several sites out there that archive reddit threads. Someone could still find the account name to a comment.

That said, using accounts with throwaway names will keep you pretty anonymous on its own.

IP, browser signature, topic browsing patterns, linguistic mannerisms. Not too hard.

Not too hard for reddit, hard enough for the average user. This means that for the purposes of having a conversation with someone else, you're basically anonymous. It's the same level of anonymity that web forums had back in the day before all user-created content started ending up on Facebook and it's progeny.

Right but I think their picture will be disjointed and incomplete. Something like 99% of all users are lurkers who never post a single comment.

I think GP meant anonymous to other users - not Reddit itself.

If you are mostly a lurker that probably works great. But I have found that the most influential/upvoted posts tend to come from established accounts with higher karma.

Just like Twitter; but most of those millions of eyeballs aren’t posting anything.