If you have the pc version, you're in luck because I believe there's a mod that makes Geralt's beard(or no beard) permanent. ^^

A mod maybe? Otherwise it would be quite complicated and annoying.

Physically Based Rendering (PBR) has more to do with textures and light how cloth, leather, metal, wood, etc look rather than physics.

The cloth physics and hair physics are more with the Havok physics engine which Fallout 4 uses.

isnt a mod, u just need to go and change your beard from the default one and it will never grow agean. The whole mechanic one work on the default hair and beard.

You mean this mod:

http://www.nexusmods.com/witcher3/mods/216/?tab=3&selected_game=952&navtag=http%3A%2F%2Fwww.nexusmods.com%2Fwitcher3%2Fajax%2Fmodimages%2F%3Fid%3D216%26user%3D1%26gid%3D952&pUp=1

One thing that bugged me about FO3 and NV was the raiders with all the fantastical haircuts, I could see them shaving all or part of their head to show they are part of some group like a basic Mohawk, top knot or pony tail but where the hell do they get all the hair gel?

I all ways chose the short cropped hair and the light beard as it looked the must utilitarian it’s the wasteland for F sake. As for TW3 (what I’ve read) most of the hair growth stages were scrapped in favour of the Beard and Hair Style DLC which I felt was a shame because a wanted to see Geralt go all ferial.

I'd personally like this if it was an option you could turn on or off.

The raiders all came from a vault that was under a pomade factory.

hobbits dont grow facial hair. at least according to any of the lord of the rings books. Unless you meant a dwarf?

Imagine sneaking up on a raider get 2' from them and all of a sudden *random squeak from rear* -3 Perception