I know
I think there are a couple of things that needs to be factored in here. One is that Football (not capitalist business based on footbal) is a closed circuit competition where the idea of growth for the sport is not really necessary for the sport (only for the business). If no player ever were to surpass Messi, Maradona or Pele, it would not necessarily be a problem for the sport of football. If revenues shrunk, the business would suffer, but not necessarily the football as a competition, as a culture, as a way of expressing oneself or getting together. So the startups-contributing-to-progress argument doesn’t really apply here.
Another point is that there is a (to me anyway) crucial difference between the clubs and the economical or legal owners or administrators of clubs. Legally, you could argue that Man Utd are the Glazer family’s private thing and it’s nobody’s business but theirs wether the club exists or disappears. But I don’t agree that that idea of ‘ownership’ covers what football clubs are or are about. Clubs belong as much to a community, to a historical sort of tribe, to the people caring for it in small and big ways, and FFP really protects a club against a passing owner or administrator bankrupting and demolishing that club for ever. And not only that, it protects the competions from being such that the owners running a, say, Leeds, Derby or Scunthorpe in the red, pressures the owners of twenty other clubs each to run their clubs in the red to avoid relegation, in a race where multiple clubs would face administration or obliteration. This is the important threat, not the threat to Man Utd or Arsenal to lose out on trophies.