I think webmasters join a affiliate program to promote a site they like and that fits with what they are wanting to do as well as paying them what they deserve. Most do not care if you have been around 10 years or 1 year, they want sites that will convert the best. I think some of the older programs get very complacent, and think just cuzz they have been around so long they can stay with that status quo, because they really see no need to do much more.