I agree. There is a big difference between getting a cut from generated search result (which is expected to change over time) and a users' blog post (which is often static after written).
And don't get with the problem with will cause to the linked sites in term of Google juice.
The google bot is capable of running some javascript, whether link juice is unchanged or not does not really apply here because they're simply adding affiliate codes, the destination page is unchanged.
And don't get with the problem with will cause to the linked sites in term of Google juice.