Most of the actual roguelike developers are here anyway, so that's me and about two other guys. I've followed reddit's RL dev and to be honest it's more for beginners. I think it's nice for them to have that kind of place to repeat the mistakes we made in the past. It's not about how "active" the forum is, I think we need to take it easy and focus on the actual development of roguelikes. If I can keep working on my projects (nothing is sure in long term) then eventually it will be a success of some kind.
There are some active developers here, and it is convenient to interact with them, which keeps me coming back.
I tend to ramble on and it usually bores people. Developers don't seem to mind when it's about their game though.
Even so, it is probably discouraging to just get feedback from one or two guys over several months.
I think the biggest problem is that most people want to talk about roguelikes within their preferred communities. There is no need for a community centered on roguelikes specifically anymore.
Here the only thing we have in common is an interest in roguelikes. But people prioritize being among their own kind and avoiding frustrating interactions with those from different internet cultures.
People want a consensus and are threatening to leave if they don't get it. Everyone likes to be told they are right, so it's only human. Before they just didn't have a choice. Now they have Reddit.
So the developers may cast a wide net to get attention, and are active on multiple sites, but people go where they feel comfortable.
And eventually, when there is nobody to play their games here, the few developers around will move on as well.
The only advantage I could see with this site is that they don't need to compete with the major roguelikes for attention.
For example, one of the problems I have reading 4chan threads is that most of the time they just talk about DCSS or TOME.
