The people who stay to fold tables after the potluck are preaching a sermon nobody hears.

Staying behind to fold tables changes the people folding more than it convinces anybody watching, because nobody is watching. There is no audience at that hour, which means the only thing happening is the quiet shaping of a person who finishes what they turn up to. Over a few years that sorts people into two kinds, and the sorting happens entirely out of sight.

Stay for the stacking next time instead of leaving with the crowd. Notice who else is still there and get to know them, because they are usually worth knowing.