That’s a fair point, although the original sub wasn’t about interacting during the episode. It was more like a book report format, but done chronologically throughout the series. So they would have a set day where the thread for each episode would go up, people could watch it in their own time, then talk with other people who also had it fresh in their minds.
You are right though, might as well start it in the main community. I am a big TOS guy but I wonder if it would be better to start with that or TNG