For clarity, Patrick is talking about inserting a record into the "usersubmitban_member" table, which is the forum-agnostic way of banning member submissions. The has_submit_permission function checks this in addition to regular group privileges.

(There is no way to ban submissions from particular IPs, we used to but it was changed to a complete IP ban system because trying to have anything fine-grained on the IP level is pointless given how easy it is to change IPs)

For Conversr (i.e. if we aren't being forum-agnostic), typically preventing a member from making member submissions might normally be achieved by putting someone on probation instead. It makes sense to allow everything from the punish form though.