Blahaj zone doesn’t do downvotes, so that side of being visible on /all is a non issue. The only thing that really seems to be an issue is that we will get the odd post intended specifically for members of the community that get visibility in /all, and a bunch of non helpful/irrelevant replies.
I think it would be nice to be able to make some posts “community members only”, but other than that, I generally think communities are helped by the increased of exposure that comes from /all