I wonder if this is truly founder friendly. Pro rata is a right given, and 7% changes a lot of the calculus when doing a round that is probably 20% to begin with. Hopefully this goes along with YC asking for less equity, or some other allowance. (IMO, most incubators already ask for much more than they're worth, though YC obviously being a bit different.)
Eh, it's really not such a big deal. Maintaining 7% in a round for 20% total only lets YC buy 1.4%. As sama said elsewhere, the difference between 20% and 18.6% (with an equivalent reduction in their $ invested) shouldn't change much for a serious VC.
Given YC's history and reputation of being very supportive of founders, any founding team is also probably better off with YC taking a cut in a round that would otherwise go to another investor, especially given that the list of investors who are as founder-friendly as YC is pretty short.
