I think the argument centers on a couple things:
Would super fans actually go less if they did not have annual passes? And if so, would they actually spend less? Or would those super fans, instead of going regularly and spending less money than a typical guest, go once or twice a year and spend significantly more?
Would more non-super fans be converted to super fans because they're attending great parks with lower crowds? Would putting an emphasis on the experience of those non-super fans lead to better experiences, better word of mouth and a greater potential for widening your audience?
I have no idea! But I think it's plausible. I absolutely don't think any park, whether it's Disneyland or Magic Mountain, has the stomach for the drop in regular revenue they'd see by dumping annual passes. But guest behavior has been altered by the introduction of a culture that incentivizes buying an annual pass. That suggests to me that the behavior can be altered.
Most guests aren't buying annual passes for ideological reasons. They're buying them for material reasons. Change the material factors on the ground and you'd see a change in behavior.