The author repeatedly mentions $XXX RSUs. It's been a while since I've worked for a pre-IPO company. Is it common for companies to give RSUs a dollar value instead of a number of shares and "heck if I know the valuation"? And how are RSUs different from straight ISOs?
https://en.wikipedia.org/wiki/Fair_market_value
Quoting them in dollars is probably not too wrong if you believe the company's valuation won't change much (which is probably true for these unicorns). Even groupon's valuation didn't drop more than one order of magnitude.