I have been following quite many ICOs over the past year. To raise awareness and knowledge of potential investors and to create the hype, almost all of the bounty campaigns use Facebook (or Twitter) as the main social media platform. Theoretically, it's logical and good idea, but when looked more closely at these campaigns, they do not seem to be very efficient.
So this staking system creates a situation, where ICOs are spending tens of thousands of dollars on Facebook bounty campaigns, but do not really get quality marketing for the money.
You seem to be mistaken about several things. 1) Bounty campaigns spend little to nothing on promotion. 2) Bounties are a great way to promote their campaigns. Yes, it might not be a truly efficient way to advertise but it doesn't need to be. ICO campaigns print their own money for free then give it away to anybody who will spam their ICO over as many platforms as possible. True, a lot of them will be advertising to nobodies or fake friends, but it doesn't matter. All they want or need is for their name to be spread out there and hope they catch some fish. What they're essentially doing is walking around with a loudspeaker shouting about the product across half the internet. Of course, half of the time it will fall on deaf ears but not always. There's always going to be idiots who want to get rich quick on the next big thing and there's always more bounty hunters that are all too eager to promote anything as long as they can get pennies out of it. As long as one person hears it then it's money well spent for the ICO (or not spent seeing as no money has been spent when you create your own for free).
Let's use this analogy: Think of ICOs like dandelions:

Dandelions spread out thousands of seeds via the wind in the hope that a few of them will find ground and spout a new plant, but many of them just end up wasted falling by the roadside or on the pavement or rotting in water etc. But a few will make it and a new plant will quickly grow with thousands more seeds to spread. ICOs are the same. They have thousands of people spreading their word but most of it is worthless and goes to waste, but they will get one or two hits that find worthwhile and fertile ground. Those users will then carry on the promotion or invest themselves and spread the same message thousands of other times and the cycle repeats. And this is why advertising doesn't need to be targeted; they just need to get their name out there and they will land some success and no money has been wasted in the process if you've printed your own monopoly money.