most of the people/programs i know who do that are simply unknowlegeable.

years ago - around 8 of them - we made our first paysite. we had a couple links to other sites on it and the site wasn't selling too badly but it seemed it could have done better. someone with some successful paysites who i knew told me that we would see a large increase in sales if we worked harder to get those surfers to our own join page rather than to other people's - so we tried it and it was true.

i mostly see this with amateur site owners where one look tells you that these aren't full time webmasters. it's most common on verotel sites. when i wrote the owners and asked for a leak-free tour link, they basically told me they would lose money if i promoted their sites - that 50% really disturbed them. after pointing out to them that 50% of $5000 was more than 0% of nothing, i moved on to sites that respected my traffic