Yeah they can't register new players if they're outside of the budget for the year in La Liga. That FFP with teeth.
In Prem / CL you just break the rules and pay for lawyers instead.
The mooted salary cap is the next evolution of FFP which means nobody new can join the party ever. The cap on salary will be 70% of revenue, so you can't grow revenue by doing what we're doing. It's just even more closed shop.