This assumes that (a) they need the money and/or (b) they could even do something they want to do with the money that they aren't already doing. I could imagine all sorts of cases where neither of these things are true, and everything's going well and according to plan. If everyone's expectations are already being met, what's the point in putting yourself on the hook to someone else for something more, regardless of how much money it is or how low the additional expectations are?
I could see the logic from a VC perspective- VCs aren't going to make any money from companies that don't take funding from them. Companies that don't take funding may as well not exist to them. VC firms themselves are businesses that make money by nurturing other businesses. That just means that all VC firms need startups to nurture, it doesn't mean that all startups must be nurtured by VC firms.
I could see the logic from a VC perspective- VCs aren't going to make any money from companies that don't take funding from them. Companies that don't take funding may as well not exist to them. VC firms themselves are businesses that make money by nurturing other businesses. That just means that all VC firms need startups to nurture, it doesn't mean that all startups must be nurtured by VC firms.