Your point is that ESPN and Fox are babes in the woods and couldn’t foresee this, which is nonsensical.
They signed contracts that allow everything that you are describing to happen because they were still OK with it.
You apparently think these publicly traded companies are not represented by competent legal and business advisors and are signing contracts they don’t like and that lose money.
You are also ignoring that TV networks destroyed the Big East and are in the process of destroying the PAC-12.
Just take the L on this point and move on.
They can forsee it, sure, but they sure as heck aren't rooting for it. It costs them more money for largely the same stuff they've already got the rights to! Why the heck would they want that!
FOX/CBS/Disney/etc would love to not have pro ratas in the contracts. But they have to. Why? Because if they say no, somebody else will agree to give it to them. And you can't not have either the SEC or Big Ten rights. This is a part of what's playing out with the Big 12, where ESPN has agreed to the increase but FOX hasn't, so the Big 12 is trying to force the league to a bigger spot where they've got to go with it too.