You are right, this is a 1:1 mirror of Reddit without any Lemmy user interactions. Since it is a one way mirror, any comments would not reach Reddit, I assume this is why it was decided to keep the communities closed down in such a way.

There are whole instances dedicated to mirroring Reddit. However a lot of people on the fediverse oppose such features, on my home instance eg. lemmit is filtered out of /all stream. https://lemmit.online/