The option is basically have 4 First Grade byes (because of Deniliquin and Hay in 2nd Grade) or Play up-to 4 "make-up" matches in First Grade. Those extra games would see First, Second and Womens teams split on occasion - and avoiding that was the absolute priority for Clubs - hence the 4 byes.
I actually think it's a testament to the clubs and SIRU, that we have basically returned to a full strength competition straight after 2020. Kudos to all those teams that took a hit in 2020 and have basically bounced back, to the point that they can nominate teams in up to 3 grades.