It's certainly true to say, as the article mentions, that the bulk of, ah, research and development at the Forge was concerned with Narrativist play and techniques, since RE and others considered this a rather neglected style of play as far as the major publishers were concerned. But I have never seen Ron write or say anything to the effect that 'Gamism and Simulationism are bad and inferior styles of play', and I don't know where you got that impression.
(He had plenty to say about the technical and social breaking-points of some popular G/S systems, particularly when they pretended to be Nar-focused and weren't, but that's another discussion.)
Going back a bit, I would say that if you're defining 'story' as 'a sequence of fictional events', then yes, it is trivially true to say that role-playing produces a story. Though, given there are such things as 'true stories', I don't know why such events would even need to be fictional, and at that point anything that ever happens is 'a story'.
The question is whether the intentions of the people playing, and/or anything about the game mechanics, encourages stories that are about something interesting. And what qualifies as 'interesting'.
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