SqlDialect.SupportsComments says whether the engine records a comment at all. True unless a dialect says otherwise, which is the opposite of the other capabilities: they describe something extra an engine might do, while this describes something nearly every engine does, so a provider built before the flag has to keep meaning yes.
comments-not-supported is a warning: documentation declared against an engine that records none, naming every object it covers in one finding rather than one per action skipped while rendering.
