"Jeff Raikes, head of the company's business group, said at a recent investor conference that while the company is against piracy, if you are going to pirate software, it hopes you pirate Microsoft software" (http://www.informationweek.com/if-youre-going-to-steal-softw...)

i.e, in the context of Facebook, a ad-blocking user is better than a non-user, since the non-user might then be using a competitor platform and encourage current ad-viewing users/developers to switch to it.