It is not overstatement to say I have basically learned to fly from pprunes private flying page,
I passed my private 20 years ago, then started flying 4 years ago after a 8 years of little or no flying, my skills were rusty in some areas to non existent in others and doubt I would have been able to pass my ppl had I been obligated to re-sit it.
I could not possibly list all the things I have learned or re-learned but here's a stab at just a few:
Runway sighting and flare judgement technique
Proper carb heat use
Engine (lycoming 360) best practiced and efficiencies at altitude
Navigation and mental math estimation and guesstimating
ATC operations and interaction
Flight instruments explained
Aerodynamics
W&B CG etc.
And many many more,
Not to blow smoke up the contributors arses but BPF,FBW,MJ,GTE and the Canadian guy with the 152 and Teal who,s name escapes me right now along with several others have been unbelievabley helpful in not only explaining things but making me go find resources to dig deeper into subjects that I did not know about or was having trouble grasping,
So to answer your question, I can say without a doubt this forum makes people better and safer pilots, it certainly has for me.