Personally, I dont think this should be universal. I agree with The Balanced Man. I am going to make sigs because that is what I like doing and I want to do it. I may be one of the more apathetic sig makers on the forums but I really dont mind when new guys with less than 5 posts want a sig. I will make sigs for people even after I made one for them fairly recently, or if they dont like a sig I have made for them or just dont wear it. Its up to them.
Anyway, if you dont think the new guys will appreciate your signature you made for them then you have the right to only make sigs for the vets, but I dont see a reason to limit other sig makers from choosing to help someone out.
"When I know nothing, the possibilities are endless."