This is a brilliant idea for YC. Having gone thru the YC experience and demo day, I would say that the scarcest resource for YC companies is that bridge between "just launched" and Series-A-fundable or profitable.
A lot of companies can be lean enough to survive this phase on their own, but a lot teams/projects are capital intensive (or slow to get revenue) amd need seed-stage help. There are precious few VCs that focus on this stage (True Ventures, First Round, USV, SoftTech, etc).
Not just for YC companies. I've gradually come to believe that the number of viable startups is more a function of the amount of angel investing going on than any other factor. VCs are useful in getting really big, but without angels startups don't survive to the point where VCs are willing to invest.
A lot of companies can be lean enough to survive this phase on their own, but a lot teams/projects are capital intensive (or slow to get revenue) amd need seed-stage help. There are precious few VCs that focus on this stage (True Ventures, First Round, USV, SoftTech, etc).