The word "scam" is often abused in cryptos, and should be avoided unless we are talking about a 100% proved scam.
I don't think that DeepOnion is a scam. They have invested too many energies in building their site and their community for it to be a scam.
HOWEVER: the dev (I think it must be a single dev, pretending there are more) seems to be a paranoid chap, which has managed with his behavior to screw a project which otherwise may have worked out.
I have applied for their so called airdrop (a signature campaign, which is fine, but call it with its true name), I was rejected because "I didn't meet the requirements" - which must be their SECRET requirements, since I was respecting their PUBLIC requirements, and so I have immediately dropped their signature and avoided the pathetic public whining that others indulge in.
All my slightly critical posts on the thread have been deleted. They simply delete everything which is not hyping the project, and the result now is that you have a 100% hypocritical community which PRETENDS to love the project but they just are terrorized to be thrown out of the so called airdrop. Rules are obscure since the dev decides which the rules are according to his mood. And all the rejected people now hate the project. A very sad show. It's a pity, it could have been a nice project. I don't think it is a scam, it is just a VERY BADLY managed project, which at first seemed very good. Perhaps they could still save it if they'd change attitude. Perhaps. Not very likely they will though. We'll see.
The best scams are the ones people but great effort into.
And realistically, almost all their content is created by people who are hoping against hope that they'll get to be added to the special 288 in the "airdrop" which is really (as you say) an advertisement campaign. They just string people along -- if you play our game and post a lot of positive stuff and write a lot of shills on facebook and bitcointalk for six weeks we "might" consider you for the airdrop then when we "change the rules!" and such nonsense.
It's a scam. And yes, I think it's a single person who doesn't actually know how to develop anything -- because he's developed exactly nothing. It's just a copy of another coin. The one "feature" they added is windows only and closed source -- and is a "feature" one could do in bitcoin in 2009.