That's just not true, and I wonder if you can cite some statistics or qualifications to back that up. In the Valley vested/exercised shares are equity, common stock, a true ownership stake in the company (see next paragraph, I'm not utopian about that means). Here, he lost his right to the stock after he vested and exercised. _No_ stock! That is profoundly at odds with industry practice that I just don't know where you are coming from in suggesting it's normal.
Standard tech industry practice does, true, allow insiders (at the time of the liquidity event) to play a variety of games to screw common shareholders. Generally, though, the bigger the event in $ terms (and this is big) the less legal room you have to play these games. For instance, as others have pointed out, you can low-ball the offer price but offer "retention bonuses" to current staff. And VCs always have their preferences. But if you keep these things on the safe side of the law, they are less and less impactful as deal size increases. I'd love to hear of a commonly employed mechanism that washes common to zero in a multi-billion dollar deal. I doubt frankly that it exists.
I agree that losing the right to exercised options in a highly public, billion dollar deal is odd. However, the end result is that guy has no stock or money. This is the same result of the "variety of games to screw common shareholders" which you seem to agree is standard tech practice. I guess there's a difference in the mechanism, but the result is the same for the guy getting screwed. Unfortunately, I cannot cite "real" statistics so feel free to write this off as internet hearsay. I should qualify that I made the mistake of spending too much time working in Boston where everyone secretly wants to be Thurston Howell III, not Steve Jobs or Larry Page. Thus, my experience is not really "the Valley" but then again neither was Skype's.
The only radical difference from standard industry practice is that it's actually spelled out in the contract.