Many would consider AAA games getting an 80 to be a mark of death. By your logic an "average" game would be like 50/100. 5/10. Not bad. Not excellent.
50 is not an "average" game. It's unplayable. I can't tell if you're being genuine or not.
Edited for moar: pokemon scarlet/violet scored low 70s, and are some of the worst reviewed games in pokemon history, scoring even lower than the universally hated BD/SP. These games were thrashed for bugs, performance issues, crashing, horrible graphics, etc. Yet they were still 7/10. By that metric, that would be "very good," right?
I stand by my point.