But banning entire subreddits because they share links to good deals on firearms and accessories is. That's because it doesn't have to do with ethics, morality, or even politeness. It's how controversial it is and if it will hurt ad profits. Gentrification in this context is making a site palatable to brands and advertisers.

Once they take large amounts of investment money they have to begin producing a return on it. From that point on users are the product and the brands are the real users.

Neither is cleaning up graffiti or opening coffee shops. Gentrification is a second-order effect of 'cleaning up' a community.