Of course, your cost of customer acquisition is likely to be way higher for an individual B2B sale than B2C, but the volumes are lower, and the revenues higher.
In both cases you need capital to understand the channels to the market, hone the proposition, build and refine the product.
In fact, I would contend that it is often cheaper to get to your first significant tranche of customers in a B2C environment - sales cycles tend to be shorter, the financial commit tends to be lower.
Agreed, you probably need a massive slug of Series A/B to grow that global B2C business significantly - but isn't that also true of a B2B proposition if you want to grow it to global scale?
The original poster's question is about idea generation, and seems to imply that crowdsourcing would provide some market validation of that idea, and "build in" a channel to that market, through those that participate in that crowd (i.e. a network generation effect).
I'm not sure that they are right - but it would be an interesting experiment that I've not seen executed in quite that way.