There are different dynamics in different countries.
P2F in itself doesnt necessarily weaken safety (although there are further arguements about the effects stresses and strains due reduced wages and high debt over a number of years)
P2F in its purest most transparent form hasnt been present in the UK for 5 years + (someone quoted 2008 on here)
P2F in its untransparent form (over paying for training and starting on lower salary for a number of years to secure a link to a "partner airline") is alive and well and has flourished in the UK in an extensive manner for a number of years
P2f doesnt create higher risk to flight safety, if a suitable training regime exists and rigid adherence to SOPs can mitigate all but the most unusual risks - which before anyone tries to counter the point could equally catch out experienced crew. As is historically proven and oft quoted on here
All that said. P2F doesnt inherently make the operation stronger nor weaker safety wise as can be seen in a number of examples whereby some british isles locos have recruited extensively in the less clear version of p2f.
And to counter that arguement nor does the more conventional route possibly via military flightcrew service and operating turbo props,
Safety couldnt and isnt It isnt the arguement or challenge for or against p2f
The damage it is doing to the industry as a whole however is a different kettle of fish. This is the only arguement available with regard to p2f. Put the safety issue to bed. It doesnt factually deserve inclusion on the merits and disadvantages of p2f
For clarity, I include all mentioned forms of p2f in my own posts the purest form and the more hidden version
FWF is on the money with one negative that p2f has brought to the party, and remains to do so.