Suppose my startup is current worth $100m. According to you, I should be able to sell 0.5% of it for $500k and give that to the employee, or offer them that 0.5% directly, right?
Well, no. I can definitely offer them that 0.5% since I control the equity, but I can't just go to a VC and tell them "hey, here's 0.5% of my shares, now give me their fair value worth of $500k".
Ever been close to a startup raising money from VCs? It simply doesn't work that way. VC investment is a big, complex package deal. They're not just going to accept whatever shares you give them, and pay you. They have their own idea of how much equity they want, how much they're willing to pay for it, how much besides equity they want (control of the company, seats at the board, various forms of preferred stock and other guarantees, etc).
Also, fixed the typo, thanks.