Many merchants simply lack the skills to convert the sale. Naturally certain products sell better online. Pharmaceuticals, informational products, intangibles, services, unique products and digital products are easier to sell and often have higher margins. Everyone wants to pin success on traffic, which is part of the problem but not the whole problem. First of all it is important to understand that some websites just will not do well with revenue sharing.
Many webmasters lack the skill-set needed to really implement revenue sharing on their site.
Many individuals falsely believe it is the road to quick riches. There are many other sites that could embrace revenue sharing but do not want to. They are still garnering large impression payments and have no desire to work on performance. This will change in the future as people begin to focus on performance and not perception. Some sites will never implement affiliate marketing because they feel it will impede their objective focus.