_Makkabeus
When enforcing this rule, RGL makes the assumption that the person who organized the scrim or pugscrim is responsible for each player's inclusion in it, which is true in almost every situation.
In my experience at least, this is far from the truth. 90% of my pugscrim experiences involve me and 1 or 2 other people all scrambling to message everyone on our friendslist, and we usually all pull 1-2 people each. I'm sure there are others who can back me up here.
_Makkabeus
Ultimately though, as a scrim organizer, you take responsibility for your team in the scrim. This rule is also by far our most widely published rule, being displayed in a large banner at the top of every banned player's page, so we feel it is reasonable to expect players to be aware of this rule.
It wasn't a scrim, it was a pugscrim. I feel like there is a big enough distinction here to where you can make it a rule, maybe define what RGL sees as a pugscrim (x players on a roster or something) instead of just blanket banning like this.