The key words here are "niche" and "engagement". I consult to a global top 20 company and can say that the only consistently rewarding spend has been from specific campaigns using a third-party platform. For example, a current promotion gives people a chance to win a phone and it has over 60,000 likes. (I can't elaborate) This type of campaign has very little engagement because people will click "like" purely to win something.
The return from pure FB ads has been less useful and can be better treated as a branding exercise.
Entertainment venues with a local audience do very well with plenty of engagement and zero spend. The DJ can whip up the crowd and they can run a variety of tactics week after week. They would regard FB as a fantastic platform. :)
I'd say that the majority of advertisers would agree with Leosghost, but some of them could be guilty of being poor marketers (boring ads, wrong targets) and a few others would have found the platform fine for their needs.