The Cowboys have been good the past two years because they have stayed away from top tier FAs and have a young roster. They were in cap purgatory for almost two decades because of situations like the Aikman release, one example of many.
The Cowboys haven't been in cap purgatory in a long, long time. That's just something those who are living in the salary cap hell past hold on to or those who think that is the reason the team doesn't spend a lot on outside free agents, which is a philosophy shift based on some high-priced FAs not proving to be worth the investment not due to a lack of cap space or the ability to create cap space.
In 2013, they signed Tony Romo to a six-year $108 million contract with $55 million guaranteed, making him the highest-paid player in Cowboys history and topping the deal that Baltimore had just given Joe Flacco.
In 2014, they signed Tyron Smith to an eight-year extension worth nearly $110 million. Other high-priced extensions have been signed by Travis Frederick and Zack Martin.
Each of these signings were based on calculations about how they fit into the cap, what the team believed the worth of the player was, etc. The Cowboys also have shown by acquiring Amari Cooper (set to earn $14 million) that it isn't cost that keeps them from being a player in free agent, it is the high price vs. expected returns on the investment. There are other examples of this that can be used, but Cooper is probably the most recent example that shows that it's about valuation for Dallas not cap space, which can be created in a variety of ways, shifted from year to year, etc.
