It's my theory that "salary cap hell" is nothing but jargon used by front offices to deflect from not wanting to make any moves i.e. Dallas every single year. You are absolutely right, any front officer worth a damn can manipulate the cap numbers. For one, the salary cap rises every single year. A $X amount hit this year isn't the same cap hit percentage wise even next year and all down the line. Eagles sign any player they want in free agency. They make trades. Able to pay all their guys they want. But we don't have a true front office with a real GM. Dallas refuses to utilize free agency except bargain hunting after all the good players are taken. When we make trades, we get the short end of the stick on both sides.
Take the Rams for example, they went all in for 2021 season and it paid off. The goal is to win it all, and they did it. Only won a few playoff games since then (still more than Dallas lol) but who cares. Dallas has no idea how to balance their future and present day. Eagles are set up to win today and in the next 5 years.