He was valuable to the Steelers. They offered him a good deal, just not as good as he wanted and so they ended up tagging him. He didn't sign and then sat out. So if your point is that the Steelers will simply fall all over a deal that offers 37 so that they can be right back at the table in two years, yeah, I don't think so. But again, they paid Ben, a QB they know can win a championship for them but only on a short term deal because I suspect they knew they didn't want him in a long term deal because of his age. There is no guarantee that they look at Dak that way. Dak has won nothing and why on earth would they pay that kind of money so that they could be back at the table in a couple of years.
As an FYI, the reporting on why the deal was turned down, from what I saw, was not guarantees. It was the length of the deal. Cowboys wanted a long term deal, Dak and his agent wanted a very short deal.