"Facebook but decentralised" is already 26 characters so that seems like a bit of a tight limit. I suppose it'll help find people who have any marketing nouse, which is the actual challenge for a project like this, not technology.
"Please implement the social network in 5 weeks or less, GitHub link to code too please"
As an aside, do the submissions have to use the Blockchain? There are already a ton of good decentralized social platforms that make no use of a blockchain whatsoever, and the majority of them inter-federate with one another.
A lot of these ICOs want developers to invest their money AND build the product for free.
I agree, there are a lot of good non-blockchain solutions to this... like most ICOs