I subscribe to a theory of the world that money tends to be the best measure of how the powers that be in any given situation view value and impact.
If CB or LT impacted the game so much, they would be the most highly paid positions after QBs. They are not.
They rank around 4th and 5th. That tells me that NFL GMs see them as 4th most important in this modern, pass happy NFL. Pass rushers OTOH are the 2nd highest paid position. They are right underneath QBs in the NFL hierarchy.
It also occurs to me that your rationale could always be applied to every position. Why pay a Von Miller or Julio Jones? You could always use that money to bolster other positions.
That rationale would always dictate that the team is full of mediocre players.
If you think about the math, you can't get a
'team full of very good players for the same price you get a couple of superstars and a bunch of good to OK players' for the simple reason that a very good player would cost between 70-80% of that superstar. So basic math says that you'd be lucky to get 2 very good players for every superstar.
So if you really want to have a share the wealth philosophy, you will have a team full of mediocre players and maybe a few who could be called good. The concept violates the Pareto principle (80/20 rule).
