Most free content on the web is free because of the advertising the providers serve along with the content. Ever since web content providers started monetizing through advertising, we have seen an ongoing competition between advertisers and ad-blockers. The technologies used on both sides of the competition have increased in sophistication and complexity. The situation is analogous to the back and forth between virus writers and virus-blocker companies, (which has matured into all malware and system protection services).
According to the linked article, Facebook simply moved into new methods of ensuring maximum exposure of the ads PAID FOR BY THEIR CUSTOMERS. There is nothing wrong with their ad-protection efforts, legally, morally, or ethically. In fact, the situation is identical to cable TV providers who prevent viewers from using the fast forward feature when watching on-demand shows.
To be clear, I do not like Facebook (A LOT), and do not trust Facebook (AT ALL). I sincerely hope that the exposure the company and its arrogant, egocentric, over-aged adolescent founder are getting in both EU and USA result in a major legislative and pubic relations takedown of this malicious company. That said, the ad-protection efforts of the company do not constitute a reasonable rock to throw at them.