This is a three part series about why financing social network and social media sites with advertising is at best very difficult. Oddly enough, people tend to resent a model where they do all the work and someone else gets all the money.
It hadn't occurred to me that advertising is especially vulnerable because if you piss off the best content providers, they'll energetically and vividly tell everyone they know about why they hate the ads and the social network which gave them a platform.
It's more obvious (but still new to me) that if an ad-supported environment is going downhill, the ads will get more intrusive and annoying, thus increasing the odds that ads will get ignored, so they get worse.
Sidetrack: There are connoisseurs of tv advertising, but I haven't seen anyone make a hobby of web ads. While spam isn't a major interest for me, I do watch its evolution in my inbox-- the latest thing is fake news headlines, like the Pope getting assassinated.