I’d have to think that a salary cap would really help parity in the league, after the first 3-5 years when contracts were stabilized under the new rules. Though I’m not sure how that would work with the relegation system, I know that in all the salary cap nonrelegating American sports leagues, it lets even smaller, small-market, lower-revenue teams compete for quality free agents every year, and (bad management aside) helps teams that are doing poorly quickly recover to winning status. I cant see why European leagues wouldnt want that, assuming they all agreed to cap salaries so that one league wouldnt poach all the top Talent.

It would help the salary-capped MLS compete for world class Talent, too, (more than just one marquee player per team) though thats probably a reason against it for European fans