In the specific context of Introcomp, Jacq’s position on this has always been the names-are-descriptions, broad-tent one: if it’s interactive, and it’s fiction, then it’s IF. (This position has not been very hard-tested, admittedly. I’m sure non-fiction parser-IF would get in, and I doubt that Canabalt would. And these positions are inevitably influenced by the fact that in our corner of the world, IF is a prestige term, and Jacq really likes The Mystery of Chimney Rock, much as zarf really likes Myst.)
In the past, the way the comp has dealt with this has been to let everything in and let the voters sort 'em out; this has been simplified because in the past the non-parser-IF entries have typically not been very good, so the less theory-minded players have been mostly in agreement with the grognards. This is plainly not the case this Introcomp.
I think that parser-IF and CYOA have a close and special relation (primarily text-based; structure driven by narrative) that’s roughly as strong as the one zarf advocates between parser-IF and first-person adventure. That said, there is a pretty obvious difference in how they are created, played and judged, and they tend towards different kinds of narrative and content. Obviously it’s legitimate for people to enjoy one and not the other. If the major comps and the XYZZYs were routinely swamped by CYOA entries, then there’d be a reasonable case for some comps to go parser-only or have separate categories; but Introcomp is not really that kind of scale. I think that, right now, we’ve got a lot to gain from watching other kinds of narrative game. And this is easier to do when we invite more people in, even if it’s only to feast upon their delicious brains.