I agree that this is indeed YC's bias, but it's incorrect that they will always advise founders in this direction. That claim is inconsistent both with my direct personal experience as a YC founder, and also with the experiences of other YC founders who I know intimately and have spoken to about these sorts of questions.
The fundamental reason claims of "being bullied" and similar are incorrect is that there's another major component to YC's incentives. Namely, YC loses out on an enormous number of great startups if there's even the slightest justified perception that they do anything close to bullying their founders.
YC's time horizon is naturally long: their biggest investments pay off over a 7-12 year time scale and almost all of their portfolio is extremely illiquid at any given time. That means they're especially culturally sensitive to actions that carry the risk of long-term negative effects, even if those actions also have positive short-term effects. Bullying founders into risking it all is just such an action, so they'd default to avoiding it even if it worked (which, by and large, it does not).