Sorry, I can see how reading my comment would give the impression that I speak from great authority, but I was mostly just voicing my own preferences and prejudices about learning. I took a look at the introductory video for your service and it seems like a very professional, carefully-structured course - I do think learning in groups can work well if there is a clear, thoughfully-conceived structure for interaction. And it must surely help that you select for motivated, intelligent people - motivation is the key to real learning at any stage in life, I'd say.
I have had some experience with attempts to get groups of people to create or work together in groups with little to no structure and it never works. But I have not had much experience with the sort of structured social learning you offer (I think architect schools do a lot of this sort of structured, group creation-cum-learning - might be worth checking out.)
I do think that locking yourself in a room with a book and focussing is important, at least to build the platform of understanding from which you can move to group interactions. That's certainly my preference for the things I teach myself, and I think it is crucial for building basic understanding and confidence with the ideas. Of course there are chokepoints, especially with something like coding where at some point you need to actually start creating, where measured, structured guidance must be immensely helpful. But I think you need a rhythm - independent learning, then taking the problems and confusions you've built up into a social setting, then independent work again - I think real, 100% focus on a problem is a solitary activity. But perhaps from your own experience with DBC you can offer me some counter-examples?