It's not even this. It's gauging the other 11 games on-par with the h2h game.
Maybe this helps - just taking off the name of each opponent (including each other, for h2h) and saying it was this outcome vs this team X or Y.
What might be the argument against that?
It's a matter of uncertainty. When you're looking at ranking teams with an H2H matchup, there are various aspects. But in absolutely zero cases have they played the same common opponents. Even if they HAD, those games would be skewed by when in the season they played each opponent, whether they played home vs away, what the weather conditions were for those games, etc.
The idea is that H2H should be important
when all else is equal. But who's to say when all else is equal? Even if they have a common opponent, what if one team played them early in the year when they were cohesive because they had a lot of returning starters, while the other played them late in the year when the opponent had a bunch of critical players injured. Is it equal just because it's the same name on the front of the jersey? I'd say no.
Nobody is saying H2H means everything. In 2018, Purdue beat Ohio State 49-20. Nobody ranked Purdue higher than OSU the next week. So it's not everything. It's useful as an added weight when everything else LOOKS close.
But it's not nothing. When you're dealing with a lot of uncertainty, maybe H2H shouldn't be
just 8.3% weighting of a 12-game slate. That doesn't mean it should be 50%, but it might mean that it's 10% of 12.5%. Especially as you get into matchups in 18-game conference schedules where teams might only have 4-5 common opponents. Or when you're dealing with two teams who played each other OOC so they have zero common opponents.
When you have uncertainty, H2H can and probably SHOULD carry more weight than just 1 of n.