Post-Seifert, I'm not so sure the argument is that dumb. Yeah, Fox ended up being at the top of the HC payscale, but he didn't start off being paid that well. It was only after he demonstrated success that JR paid him. If JR wants to sign a veteran coach in the league that's had success in the past, he's going to have to pay big right off the bat, and I'm not sure JR is ready to do that.
We've only had two coaches post Seifert, neither of which were veteran coaches when signed. That's not exactly a large enough sample size to denote a trend.