I suppose the difference here is the type of success being discussed. Sure, we could pull mediocre recruiting classes and still easily get to where Kentucky/Arky are now as long as we have good coaching. But while Kentucky and Arky are good, they aren't serious national title threats, and likely never will be. So if the goal is to simply get to a level where we are a consistent 7-9 win team, with the occasional 10 win season mixed in, then recruiting rankings shouldn't matter too much. But no team has won the title in the last like 20 years of recruiting rankings that didn't have consistent top 10ish classes.
As far as teams like Iowa, Pitt, TCU, etc, you can regularly compete for a conference title and even be in the playoff picture with mediocre talent in other conferences. In the Big 10, the only teams pulling consistent top 10-15 classes are Ohio State, Penn State, and Michigan, and all 3 are in the same division. Iowa and Wisconsin are in the West. Odds are, the Big 10 West will produce at least one regular season 10 win team every season. Then all they have to do is have an upset in the conference title game in order to get into the playoffs. Same for the Big 12. Texas and OU are the only schools pulling elite classes, so if you have a good team, you only need to upset 2 schools that are clearly more talented than you.
For Tennessee to be in the national title hunt with recruiting classes in the 20s-30s range, they'd have to upset at least 3 schools (probably 4) who have a clear talent advantage. They'd also have to beat at least 2-3 other schools that are on the same level recruiting wise. This is why Kentucky and Arky will likely never be serious National title threats, unless their recruiting improved dramatically.