Affiliates are considered to be a major force for many businesses, yet they are often blamed for any pitfalls such as if a business site gets a Google penalty. In reality affiliates help a great deal by:
affecting the bounce rates,
have a direct impact on user experience,
they complement SEO efforts.
It could be that your affiliates rank well, and thus this helps a lot if your site is not gaining very good SERP. Effectively affiliates could ultimately help to knock down the links of your competitors when an online search is made, which is great!