Originally posted by Ziggystardust
It's very simple. The notes of the publisher aren't meant to be part of the story - i.e. adding to the continuity in any measure and is simply just a interpretation of the events for the purposes of selling and aren't always checked over by the author. And this is the case for pretty much every book that was ever written. You can see several different publisher blurbs from various companies that have published harry potter, not one of them introduce anything new to the continuity. So we're left with Plagueis' opinion on the matter.
Alright, let's cycle through your complaints, which seem to align closely with Neph's:
1. "They aren't a part of the story" - since when does information have to be narrative to constitute a part of the official literature? What about sourcebooks, guides, visual dictionaries, etc.? None of these add new stories to the universe, but they're still accepted as parts of the continuity. This is, as we'll see to be a pattern, a made-up rule.
2. "just an interpretation of events" - so are sourcebooks, guides, visual dictionaries, and even novelizations and other adaptations. There is, once again, no actual policy suggesting that interpretative sources don't count. And if there's a reason to discount them, nobody has actually made it - they just restate their reservations as justification for themselves, .i.e. here.
3. "they're made to sell" - rather horribly naive given that this applies to basically everything, and still another arbitrary rule. Are you prepared to vet every source available to us by guessing which author is in it for the art, and which is in it for the money? Where's your line going to be? You don't even know that the publisher doesn't care about the story, and is using the blurb to add excitement or wonder to it - it's another arbitrary claim, and even if it were true, irrelevant to the question of whether it counts as evidence.
4. "not checked over by the author" - the author is perfectly capable of checking or objecting to the blurb. But even if they were not, there's no rule suggesting that authors have exclusive monopolies over their creation. They already have editors, the publishers already influence which books they create, and others can put their characters into sourcebooks and add new information on that. What matter is whether Lucasarts/films approves of the material, not whether any individual author does. This complaint is, yet again, another arbitrary rule.
Nobody here is suggesting that publisher's blurbs are sacrosanct; like all other aspects of the literature, they must be taken into account with the surrounding evidence. But here, you offer no "surrounding evidence" to force discrediting or reinterpreting the blurb; you just offer your gut hidden behind a bunch of circular criteria for canon that you made up.
Now, if you want to explain why something being on the outside of the story rather than the inside is grounds to dismiss it, you're welcome to present your case. But your whole post here has been a thinly veiled exercise in circular argumentation - "this arbitrary rule of mine is right because of these five other arbitrary rules of mine that justify each other!"