It's because there is no uniformity in college football. Some conferences play 8 conference games, some play 9, giving them fewer non-con slots available. Schedules are made by different teams at different times. So, you want a series with Ohio State, but due to them playing 9 conference games, and having already contracted out the other available slots (or be in serious discussions with others) then this is the only available window that Georgia and Ohio State had.
And quite honestly, the available slots per year are really only 1 or 2. Because no power 5 team is going to schedule 3 non-con games against fellow powers. So really we are talking about only 1 available slot on each schedule per year. Well consider they've got an open window in 2025, but nothing the following year. So a home and home won't work. So then you've got to look for the first window of 2 consecutive years.
It's this way because the sport is completely disjointed. The complete opposite of the neatness of the NFL, for example. Which, I happen to love even if it means absurdities such as this.