I don't think it's fair to bunch all 400+ Y Combinator companies together like this. You'll probably find good and bad benefits packages with the same frequency across all small startups. Y Combinator certainly does not get their hands dirty in the operational, HR, or recruitment strategies of their funded companies; that's really up to the founders.
Perhaps what you want to say is that you don't like the benefits packages that startups with young founders provide, because they don't understand what a more senior engineer expects on that side of the compensation equation. That might be more fair.
Perhaps what you want to say is that you don't like the benefits packages that startups with young founders provide, because they don't understand what a more senior engineer expects on that side of the compensation equation. That might be more fair.