It’s a difference in style that leads to the substance of parity between the sports. It’s OK to have good and bad franchises in a sport, I agree, and football has those too. (See Lions, Detroit.)
But even beyond that, it’s a different animal when there are also systemic issues that lead to the lack of parity, versus merely competence differences among the individual franchises. One can point to Tampa and say, look, there’s a franchise that doesn’t spend big bucks on free agents and they’re winning. But do the people of Tampa love love love their team that recycles its entire roster every four or five seasons because they won’t bid to keep stars longer than that? The stadium is in a ****ty location, sure, but I’d bet unusually low roster stability must have something to do with the weak attendance, too.
What I don’t know is whether there’s any causation between inability/disinclination to sign and keep big stars, and a team’s inability to finally win a ring. Many people might say that idea is ridiculous on its face, because the playoffs are a crapshoot 100%, but remember, Oakland had the same issue in the playoffs when they were winning 90+ every year, too. It’s only two anecdotes so I’m not fully subscribing to the hypothesis yet, but I also don’t think it can be rejected out of hand for lack of sample size.