I'm completely guessing here...but iffn I were to start a new link list, I'd probably ask that submitters use the category specific links for a few reasons.
Nobody builds something like a link list with aspirations of failure. It makes sense to me that they are striving for becoming established, known, and big! So, when it grows and there are tons of sites to send surfers to, that would not be when I'd want to totally rearrange and organize my LL site. I'd prefer to have it organized and together from the start.
I can also see the benefit of a newer LL recip nestled amongst others in a table...a surfer already visiting a certain niche is hungry for more of this, would that surfer choose one that specifies that there's more of this type to click here, or just a generic porn link?
I dunno, it makes sense to me, not because they want to be tyrannical (sp?) but successful and are forward thinkers.
(ok, this is were I apologize if I'm also in need of more coffee this morning before I make more nonsense statements)