Holman was writing about slow exits, and how they keep employees illiquid and even claw back equity from those that leave.
Snap is not a slow exit. It may or may not produce a bunch of millionaires but it's definitely not what Holman was complaining about. In fact he would probably praise them for going public ASAP, like the old days.
Mmh. Yes, but I think the two are two sides of the same coin. Not only are exits rarer, but the companies who do exit produce fewer people who are then in a position to keep the innovation cycle going. Holman touches on a few reasons why in his post: "...concentration of wealth, and legal stipulations like gnarly 90 day exercise windows".