I think P2F isn't necessarily a safety problem, but a workers' rights problem.
I think associating P2F directly to reduced safety is a mistake and an exaggeration. It's true that, in some cases, P2F could indirectly affect safety, but many other life circumstances could affect safety in the same way and nobody is creating facebook groups against them (divorces, breakups, living in ****ty countries...). It's still a bad thing, and I admit a safety debate could be seen as a more effective way to present the case to the public opinion.
The thing is, P2F is still something we should fight against because it creates a state of unfair competition among candidates.
P2F is not equal to paid type rating. If airlines can't afford training programs, sure, let the applicants pay for training, but after successful completion of the courses, the pilot should be hired, and paid accordingly for his or her services. Otherwise, it would be clear that the airline had no intentions of keeping those new pilots, and that it would just get new ones paying for flying, time after time, forever.
So my opinion is that P2F is not necessarily a safety problem, but a workers' rights problem and, this also being a threat to the industry, it should be treated as such. I'm sure it's easily demonstrable that setting a basic cost of 200.000€ for anyone aspiring for a remote chance to make a living flying big irons, can't be a good thing in the long run...