I experienced exactly this a couple of years ago in /r/espresso. Fortunately the low-quality memespam pushed me to look for alternatives, and I found Home Barista forums, one of the best quality web forums I've ever participated in.

Something similar happened to me in the bicycle space, which turns out to have a lot of forum activity as well. Seems some of the oldguard never switched to Reddit in the first place in both communities.