They were not the first company with simulation games either, which suggests that they have a secret formula figured out for how to build and market these games. The restrictions Facebook places on viral marketing hurt everybody else and only put Zynga further ahead.
As for IP, the reason why Pincus is a shareholder in Facebook, along with Reid Hoffman, is because Facebook licensed social networking patents from him. He has been in the field for a long time, long before the mainstream press was hot on 'social', and he has significant IP holdings in the space, which are with Zynga.
The other companies you point out are now being prices in the same way music and movie studios are - ie. as hit-based businesses. Gaming budgets have become so large, and so much of it is tie-ins and licensing, that for each of these companies it is one or two big hits or franchises plus dozens of big misses. They are all big, large and inefficient companies - again, no different to the music and movie studios.
The only one of the three performing well is Activision, and that is mostly because of the recurring revenue from the Blizzard merger. Prior to that they were also in a lot of trouble (at the time of the merger they were worth $18B, now $12B). EA has been bleeding money for years and unsure what to do - even their big old hits such as Guitar Hero and the FIFA franchise are costing them money. Take-Two hasn't made a profit in 3 of the past 4 years, and is currently valued at less than the revenue it receives from a single release of GTA - so the market has no confidence in them at all.
It is actually the traditional gaming houses who are having trouble producing constant hits. If Activision lost World of Warcraft tomorrow they would be in a world of trouble. EA and Take-Two already are. The virtual goods market is showing no signs of slowing down, $2B last year and growing at 50%+. This is as big a shift in the gaming market as arcades to consoles was, with EA being the only one of the three making a decent effort in the new market (4th largest, but almost 10 times smaller than Zynga)
Zynga, which represents the 'new model' is over 1,000 employees (vs 7,600, 7,600 and 2202 respectively) and near $2B this year in revenue (vs 4.47B, 3.5B and 0.7B respectively), and while there is a chance that their valuation will enter over-blown territory, there is little doubt that they are absolutely killing the old gaming companies atm. It might not be Zynga that is #1 in 10 years time, but it will be somebody - and atm nobody is even challenging Zynga in this space - but you seem to be arguing against a shift that is by all accounts very real.
Edit: and on the issue of Hold'em - with the government shutting down the online poker sites in the USA it has seen a spike in play, which means it will be in a very good position if UEGA is repealed or if poker is found by a court decision to not be gambling.