Take a look at the stats for these leagues and it tells you why there needs to be financial controls and even stronger financial controls within the game:
La Liga
In the past 40 years, the league has been dominated by Real Madrid and Barcelona
Barcelona:18
Real Madrid: 16
Bundesliga
In the past 40 years the league has been dominated by one team, Bayern Munich with 25 league titles
Ligue 1
Since PSG was bought by Qatari investors in 2011, PSG has won 10 league titles in 12 years
Serie A
In the past 20 years the league has been dominated by Juventus with 14 titles
The reason I have not included Man United in this list is because all these clubs have one major difference, they continued to dominate their respective league over the years with multiple different managers. United has not dominated the league ever since Alex Ferguson left hence why I have not included them in the list.
But for arguments sake lets look at Man United's dominance of the premier league from it's introduction. The premier league was founded in 1993. Alex Ferguson retired from the club in 2013. He was therefore at the helm of United for 20 years in the PL and in those 20 years the team won 13 league titles and came 2nd 5 times. That's dominance by anybody's standard.
But when United were dominating the premier league, they did so in the same manner as all the other teams in the list, they were out spending all their rivals on wages, transfer costs and sponsorships which is why they were able to keep themselves at the top.
The PL introduced it's financial rules to stop another Man United dominance occurring. We are already seeing the dominance of Man City. Do England league fans want another dominance like United happening again? of course they don't. Fans already got pissed off with United being so dominant and still to this day many fans are pissed off at United for their league dominance. I therefore have no doubt they do not want to see another team dominate the league like United did. Look at Bayern Munich and their dominance of the Bundesliga. Do fans want to see that dominance with the PL because that is what will happen if Man City are able to get the financial fair play rules thrown out over 3rd party sponsorship.