Heard Broaddus/Voch debating this yesterday after the Garrett trade. We discussed after the Parsons trade that these elite edge rushers weren't on championship level teams. The defensive stars who have been apart of super bowl championships over the last decade or so have been those elite defensive tackles.
Really think it is all about the salary these players command. When you start to pay an edge rusher QB level type of money it really affect the team's salary cap. Just look at what Green Bay did this offseason, lost a ton of players that they couldn't afford to retain.
When you look at the DT market, the highest paid gets about 32 per year, that is pretty much the cost of the average edge rusher in today's game, where the highest paid is Will Anderson at 50 million.