The thing is, because of Facebook's algorithm, even a hobby DIY group doesn't get treated as a completely-neutral public utility space.

FB will still prioritize things that generate interactions. So if little bits of controversy slip into the DIY discussions, that's still what bubbles to the top of everyone's feed.

It hasn't necessarily happened to your group, it may not necessarily happen, but the point is that this is what the algorithm was optimized to do.