fair. the important thing here is that IPO is not the only way to liquidity for early employees

Well, I'm not sure it is. People are pretty aware of salaries already for example. This was about stock options specifically.

Right so for options, when the employee leaves the company, they can convert them to shares, and then there are ways for them to sell those shares somehow, and it results in cash money somewhere down the road that isn't just the salary.