Sorry, BritCard, but you are simply not basing your arguments on facts.
First, if you read the CBA you will see that the salary cap is based on revenue, and unless you believe that the revenue (especially TV deals) will suddenly start to plummet (for the first time probably ever), the salary cap will continue rising. This year the salary cap is up 25.7 million from 2021, and the amount has gone up ten years in a row.
Second, there is the history. DaHilg has already explained in this thread how you can look at the Saints and the Rams as the best examples.
As you see, your analogy about domestic finances makes sense from a theoretical standpoint, but since the salary cap goes up so much each year, it makes no sense to talk about it as a tool that restrict teams from doing business. If your salary increased 12-16% each year - and you knew with almost certainty that it would continue to happen for the next many, many years - your budget for domestic finances would be a lot easier to make.
It is a ghost to talk about the salary cap as anything else than a bad excuse.