I'm mostly going to chime in with what others have said. I see a few main reasons.
Patreon split the community. It split the community in terms of who has access to which content, which limits discussion to certain groups; it moved many reddit/forum discussions to patreon videos (post show videos, announcements, Q&A's); and it moved where people can respond to that content (patreon posts vs. this website). As a result, I feel like now the only good way to interact with the community is through live chat. Patreon's comment system doesn't really encourage back and forth discussion as well as a site like Reddit does...and feels more like Youtube comments. On this website, it feels weird to discuss Patreon-only topics...but that's where most of the interesting/discussion generating content is.
Rollplay feels less accessible now. The live show times are bad for EU and, at least for me, they are bad for east coast US. In addition to that, the shorter form/jump-in-whenever shows of R&D and West Marches no longer exist. When One Shots happen, they help fill that void, but I watch a lot less Rollplay now because I can't always keep up on a weekly basis, and it seems like the channel is primarily focused on longer shows that benefit a lot from knowing what came before.