There are several factors that ensure better Signal to Noise ratios in communities.
Protective Moats, specific technical subject matter, for example.
Essentially it boils down to difficulty to engage, or non trivial effort required to engage.
The factors you mentioned have little impact on the behavior of the sub, which is mostly influenced by the people and norms of behavior, over the UI.
There are several factors that ensure better Signal to Noise ratios in communities.
Protective Moats, specific technical subject matter, for example.
Essentially it boils down to difficulty to engage, or non trivial effort required to engage.
The factors you mentioned have little impact on the behavior of the sub, which is mostly influenced by the people and norms of behavior, over the UI.