> The problem with at least Facebook and Twitter (and possibly Google) in this analysis is that their attention-grabbing model requires them to analyse and interfere with the data which is coming through their systems.

Not to mention a completely different topic - ads for scams. When I create a new ad on FB, they keep it in review for at least a couple of hours. But every day I see dozens of ads that are obviously dishonest. Some financial scams, ads for some fishy schemes, some of them badly translated.

When you are a publisher and accept an ad, obviously it's very tempting to claim all responsibility is with the advertiser (it is not, although details vary between jurisdictions). But even if you didn't have any responsibility legally, it still feels terribly wrong from the ethical point of view to get rich by helping scammers cheat some poor chaps of their money.