You have a very good example of dandelions, except there's one big difference. Dandelions, cannot change their way of distribution. They cannot make their distribution more effective.
On the other hand, ICOs can, and in my opinion, they should. Doesn't matter that they ''print money''. Investors are buying the stake in the company, and I'm sure that most investors wouldn't want that their hard earned money is spent ineffectively.
Just because the bounty manager is ''playing'' with someone else's money, doesn't give him/her the right to spend it ineffectively.
Neither can ICOs change their advertising model because they don't have the advertising budget to do it. The money you invest in these companies is not invested in anything and 99% of the time the money just goes directly into the pockets of people who are running the ICO and that's all they're for. The guise of the ICO is just some sham to make people think they're investing in something worthwhile so they give them some money. ICOs only advertise in the places where they can get away with doing it for free. What effective ways do you think they should be spending it? As I said, they don't care as long as they're blasting their name out there in any way they can and via bitcointalk, Facebook and twitter etc is essentially the only way. They're spam campaigns at the end of the day that want to reach as far and wide as possible, and not some sophisticated advertising campaign promoting an established or up and coming brand. Most of them are fly by night scammers who want as much money as quickly as possible and then to run with the money. They spam their message in as many places as they can and hope they catch some flies. They can't do specific targeted advertisements on say YouTube or Facebook because they cost money and they can only pay people in monopoly money that they've created themselves so that's why they're limited in what they can do and that's why paying people to spam facebook/twitter is the only way.