Having had the chance to compare Yuletide with other exchanges now, I have to say:
If I ever stop doing Yuletide, it's because request details are hidden until assignments go out. I simply don't enjoy rolling the lottery on my assignment to that extent, and writing 1000 words of fic that aren't for myself but that I also know can't perfectly satisfy the recipient is a chore. I have a much better time in exchanges where I'm able to game for my recipient.
More broadly speaking, I suspect there are a few people like me for whom the trade-offs that Yuletide does in order to make matching easier are not worth the benefits.
Re: Why isn't Yuletide growing?
If I ever stop doing Yuletide, it's because request details are hidden until assignments go out. I simply don't enjoy rolling the lottery on my assignment to that extent, and writing 1000 words of fic that aren't for myself but that I also know can't perfectly satisfy the recipient is a chore. I have a much better time in exchanges where I'm able to game for my recipient.
More broadly speaking, I suspect there are a few people like me for whom the trade-offs that Yuletide does in order to make matching easier are not worth the benefits.