prosfilaes
Adventurer
Show me the tons of evidence that demonstrates it's the OGL that is the source of their success, as opposed to the people running Paizo.
That's an absurd division. Any number of things vitally contributed to their success; their publication in English, their choice to incorporate in a capitalist country instead of a communist country, etc. Nothing is the source of their success as opposed to everything else. A Great Man analysis tells you that everything is done by Great Men, but a real analysis of history tells you that's a very superficial analysis and that things are complicated.
Look at Malhavoc Press for a counter-example (and also for an example of a company that did well without being particularly free with it's own content).
The license on The Book of Experimental Might is pretty much the same as on any Paizo book. Malhavoc Press was primarily a D20 company and had above average freedom on their content for a D20 company (which is not being saying much, in my opinion). As for Arcana Evolved, they simply weren't playing in the same ballpark as Paizo's Pathfinder, and certainly didn't "do well" in the sense that Paizo did well.