No one is conditioned to think under 70 is bad by the scores alone.
What happens is people play the 7/10 games, and some more often find them lacking to the point they have a dull time, while others more often find something that amounts to more than the sum of its parts.
And after a while, the former realize many or even most 7/10 games have issues they can't look past, while the latter know they will be able to enjoy the majority of them.
These games aren't "underrated", they usually do have flaws that deserve a lower score. Rage 2 has a lot of issues, but some people can look past them.
Of course reviewers who look for flaws are going to find them and list them, and reviewers tend to play more games than your average gamer. So flaws become more apparent.
There are many factors at play here. It's reviews stating flaws, rating games based on flaws and positives, but some games amount to more than that sum.
Sometimes that is hard to see when you can't see past the flaws, and some people can't do that, and I think being in a profession where you actively look for flaws and positives will make it harder for reviewers to recognize "more than the sum" titles.
There's no real issue here, imo. Rage 2 looks fun, I think I'll enjoy it, but the 2 hours I spent and the reviews prove it ver likely won't be worth full price.
7/10 is fair: open world IS a step back in many ways, NPCs DO reel off slow dialogue while you stand in locked rooms, you DO drive through masses of empty space between tiny bouts of combat, etc...
If these things don't bother you, great, but they are poor aspects of design. Being able to look past them doesn't make them good aspects.
