Side discussions are inevitable — and make this place more interesting and fun — most of the time.
I don’t know how much this is about linear thinking vs. expectations of a thread / board and also respect and allowing space for others to participate.
There are threads that seek specific help or information — in those cases, it would be nice if that query was actually answered, both for the OP and for future searches.
In some cases, a community forms around a theme, and a specific thread topic doesn’t even matter, because largely the same people populate all the threads on that theme. To an unfamiliar eye, the same discussion (or debate) is happening over and over again, but hey, maybe that’s what they enjoy, so I wouldn’t call that tangential.
In other cases, some drift is part of the discussion flow of a community that has built up over time (like WFD). But someone new comes in every so often and asks that the thread become more regimented — completely missing that things don’t need to function exactly as they think they “should” — they can just become a part of what’s already there.
This happens in the inverse with new threads occasionally too — someone seeds a discussion, but then doesn’t like the direction “their” thread took. Well, threads flow like conversations in real life — all over the place.
But I do also think there are some posters who prefer a tangential discussion to actual thread topics — you can spot them when there’s little or no contribution to the topic itself, they’re just there because it’s what’s active at the moment, To me those are intentional, not organic, drifts. There’s a better place for that (usually somewhere in Not About Food).
Always good to keep in mind that HO is a community that’s been around for a while, but it’s on all of us to keep it pleasant and fun. Because when it stops being that way, people leave, and then you’re just left talking to yourself, lol.