In the case of cost per mille/click, the publisher is not concerned about whether a visitor is a member of the audience that the advertiser tries to attract and is able to convert, because at this point the publisher has already earned his commission. This leaves the greater, and, in case of cost per mille, the full risk and loss (if the visitor cannot be converted) to the advertiser.
Since you’re essentially a freelancer, you get ultimate independence in setting your own goals, redirecting your path when you feel so inclined, choosing the products that interest you, and even determining your own hours. This convenience means you can diversify your portfolio if you like or focus solely on simple and straightforward campaigns. You’ll also be free from company restrictions and regulations as well as ill-performing teams.