It's hard to anonymize a data set that's both small and has a lot of variation.
But as we all know so well the "startup outcomes" follow a power law. Dropbox and AirBnB make for a great YC PR, but are certainly nothing like a statistical mean outcome (aka "expected value").
I'd say it is a pretty reasonable thing to postulate that "doing things YC way" would result in a worse expected outcome for an individual founder vs. retaining control of a profitable business. If this statement is wrong please refute it with data.
The way things are right now, YC is selling the "possibility" of becoming an outlier, while downplaying what "typical results" usually look like. If you were in a consumer product market it could likely break FTC rules on truth in advertising: http://www.ftc.gov/speeches/starek/nima96d4.shtm
EDIT / RESPONSE 1: This is not an "accusation". I am simply stating as fact that YC's model is focused on promoting its largest outlier successes (which form the bulk of YC portfolio value) while releasing no real data on the "mean outcome". Take it for what it is worth. As far as my statement about comparing "mean outcomes" it is obviously just a subjective judgement based on anecdotal evidence because there is no publicly released data from YC.
EDIT / RESPONSE 2: Let's be realistic. Any VC firm can release % of IPOs, M&A and failures as well as IRR figures and exit bands. There is no reason to include any company-specific proprietary data. The only reason for YC to not give such estimates is because it would highlight the fact that most startups are nothing like Dropbox.
Also, his company has spent time and money to gain access to data that should help him pick emerging companies. I'm not sure why you would feel entitled to that. I'm sure they are working on some data project to help automate decisions on applicants, if not they will be eventually.
That data will give them an edge when making offers. When you are in a position where asymmetrical information is working to your advantage why would anyone give that up?
If they have to rely on "asymmetrical information" to get access to deal flow and make competitive offers and if releasing the data would hurt their attractiveness to prospective investees, why exactly are they a good deal for entrepreneurs (who can actually build a business)?
There is an old saying if you do not know who is the fool at the poker table, that's you.