To me it is and it isn't in its current model (hence they're changing it). It's also a sham in general.
Chelsea spending £1billion and finishing midtable isn't sustainable. That kind of spending upset and is disruptive to the market.
However, they can recoup a lot of that with player sales within the 3 years. Which is basically what all the other clubs outside the top 6 are having to do at some point from spending in general. If they even attempt to spend a little bit over budget to climb a few places, they'll have to look over their shoulders.
The other 6 clubs do not have that worry about. So there's never going to be a real shift in competition.
But the flip side is, even without FFP there was no real disruption apart from the league allowing blood and oil money in.
FFP was also introduced by UeFa when clubs like Monaco, City, and PSG were taken over and decided to go silly spending. Gatecrashing the elite.
I could be wrong but I've not seen evidence of FFP stopping clubs from going insolvent. In the championship and lower leagues, the punishments have actually killed football clubs.
People forget that the fit and proper owner test in English football was brought in to stop clubs from going under, not FFP.
If they wanted to PREVENT clubs from financial peril, the penalties would be removed.
The problems with PSR and FFP are this:
1. The calculation is forward looking (you need to budget against many variables)
2. The punishment is backward looking (it can't possibly be applied in the offending year).
How you remove the uncertainty is to create a hard cap. Use the 70% of revenue as an example.
A club's cap would be determined by the prior year's revenue. An adjustment would be made for the promoted clubs.
Clubs would know how much they could spend on wages and fees on July 1st of each year.
The that calculation is submitted to the league and is updated for each transaction.
Any transactions that fall afoul the cap are not registered. No one can go over their cap, so there can be no punishment.
This would require oversight and strict rules on revenues, which there should be anyway.
But as I said before, none of this is about sustainable, responsible ownership. It's about codifying profitability and certainty for the largest clubs.