One problem, I think, is technical. The interoperability challenge is big, in this area and in many others... EU is aware of that, and is also aware that this is specially important for EU, in order to accelerate proceedings (even get some automated proceedings) within Member countries. So they're investing on that in many areas (ex. Healthcare systems), why not in this one?
The other problem is mainly cultural/organizational: supporting and/or funding bodies might want to have their own mobilisation tool, serve by themselves their audience and not redirect it to others. But then, they set up something they have no resources and/or capabilities to maintain at a good quality level. Here, it is important to raise awareness on how useful are open, collaborative environments, and tools, if privacy boundaries are properly consedered. And help them to understand that their role in the ecosystem is not at all challenge: they still will own their "community" and their role in relation to it, as the tool will serve to optimize positive outputs coming from the relations within this community, but not to create a detached one, alienating the platform users form the community they came from when they started to use the platform.
A very successful EU-awarded experience in Spain is that one of Valnalón Educa, that has even gone lower in the education system, to primary education... http://www.valnalon.com/en/valnalon_educa/ Of course, this is an initiative which doesn't end up with real start ups to set up, but it's been very successful when engaging educational establishments and local context (parents, community) in the educational process regarding entrepreneurship of their children.
The backbone of this idea, I think, it's the scope of its audince: veeeery young entrepreneurs (15-19 years). I see the point of encouraging the "entrepreneurship culture"; however, if you think of the projects coming out of this, ready to be considered for investment... Which profile of investors do you see interested in engaging? Would they engage as sponsor of a social initiative or as actual, very business-oriented, investors? Which specific support will need this very young people, still finding their path, on the top of what an older entrepreneur (dunno, 25-35 years, or even older) would need?