You weren't stating "Pathfinder followed the OGL, therefore it was caused by the OGL," though for what it's worth, that's also a fallacious statement. Rather, you were stating that WotC wouldn't use the OGL again because the OGL led to Paizo's Pathfinder becoming a major competitor to WotC's D&D - that is a fallacious statement, because simply releasing the OGL did not necessarily cause Pathfinder to become a success, and it certainly didn't cause it to become a success to the point of being a major competitor to D&D.
Once again: They won't use it because they don't want to further create new competitors. Without it, Paizo wouldn't be a competitor, period. Sure, there are hypothetical situations where they could had OGL and Paizo wouldn't be a competitor. So what?
WotC stored pyrotechnic stuff in his garden. Due some "perfect storm", a few circumstances were added (a dry sunny day, someone lighted a cigarrette, strong wind). There was an explosion. WotC learned his stuff: Even if the pyrotechnic accident was not caused *because* he had stuff in his garden, (rather it was caused by several circumstances), the accident would be *impossible* without pyrotechnic stuff in his garden. Regardless of how sunny is the day, how many cigarrettes are lit, and how much wind is blowing, without pyrotechnics, there's no pyrotechnic explosion.
Back to Paizo: WotC released OGL. Due to a serie of circumstances (4e not being liked by some player base, GSL being lackluster, bad communication, and whatever you want to add), Paizo made a strong D&D competitor. But without OGL, Paizo *could not* build a strong OGL competitor, regardless of any other circumstance (including 4e not being good for some people, GSL, bad communication, and any other you want to add). OGL didn't *create* Pathfinder, but Pathfinder *wouldn't be possible* without OGL. Just like a seed does not create a plant (it needs also water and sun), or a mother does not create a baby (it needs also a father). But you can't have plants without seeds, or babies without mothers.
To reiterate, you stated that WotC would avoid using the OGL again because of how much of a success Pathfinder is. That's a post hoc ergo propter hoc fallacy.
It's not. It would be, if OGL wouldn't be a necesary condition to have Pathfinder. But it is. I would avoid using rose seeds because I don't want roses in my garden too. And yes, seeds aren't the cause roses grow: they need a plethora of other things.