My observation is the worst aspect of monetization is on the communities themselves. For the first half, say, it was standard spectrum: some trolls and schmucks but for the most part regular folks with something to say. April Fools projects from the admins wowed us year after year at the creativity and cordiality.
Then came the ads and the apps, no picnic but down in the subs was a new problem: site policy. At some point, subs and posts were getting yanked or even altered by admins. Censorship, astroturfing, shilling, kowtowing to foreign investors, the whole political manipulation thing: you couldn't trust anybody's motivations anymore in a conversation. Most lately, the standard disney/youtube-ification has started.
I'm almost done, too.