The Buffy comics aren't the same status as the television show because... they're not the television show. They have reached only a fraction of the show's audience. I can assume safely that all of my readers have watched the show. I can't assume they've read the comics. In fact, I can be sure that most of them haven't. So I can't take knowledge of "The Long Way Home" for granted the way I can take knowledge of "Band Candy" for granted.
Canon is our shared knowledge. It is the structure upon which I hang my stories. It is what I do not have to explain to my readers, and what baffles me when I read stories in fandoms I know nothing about. I'm not particularly tied down by canon; I don't feel any need to write stories that stay within it. But I do want to know that my readers share it with me.
So bing, right there I've got a reason not to treat the Buffy comics as canon when I write.
As
Anyway, I'm into
And maybe I'll write some Giles/Spike to demonstrate my agreement.