Independent content creators are on fire all over YouTube, especially the ones who's content is predominantly focused on reporting news, events and "Natural Calamities". According to YouTube the following contents are deemed as "advertiser unfriendly":

Sexually suggestive content, including partial nudity and sexual humor

Violence, including display of serious injury and events related to violent extremism

Inappropriate language, including harassment, profanity and vulgar language

Promotion of drugs and regulated substances, including selling, use and abuse of such items

Controversial or sensitive subjects and events, including subjects related to war, political conflicts, natural disasters - - and tragedies, even if graphic imagery is not shown

Youtube has clearly stated that any videos containing such content shall be demonetized. This essentially means that there would be no ads shown alongside the video which would result in no income generated for the creator through Adsense, a program through which creators get a part of the ad revenue generated from the viewership of their content.

Youtube has argued that their advertisers do not like their products being marketed alongside controversial or objectionable content. The advertisers fear that it might indicate their products getting associated with the content which might negatively impact how the product is received by the viewers.

As expected, the response to this has been outrage from the creators. Several videos have been published accusing Youtube of using this as a method of rooting out the content which it doesn't approve of but cannot censor. Leading the pack is this 10 minute rant from Philip De Franko, who was one of the firsts to bring this issue to light.