Here's something also for you; Japanese writing tends not to care about continuity or consistency like western writing tries to, and pretty much doesn't go "well, that's old info, so it's no longer canon", they tend to just leave it there because it's information already established, even if it's not updated. japanese writing doesn't often to retcons, they just do whatever the current head writer wants and balls on it if it's not matching up quite right. In Deadly Fortune's case, it was essentially like, say....El Hazard the animated series vs El Hazard the OAV series; two different versions of the same story with a number of major differences. DF is what Bingo wanted, so it's his "pocket" canon, but is not the canon of DMC4. In the case of the DMC1 novel...it was written specifically to give that background info for DMC1, from both the writer AND from Kamiya. That's a whole lot different from "Ex employee writing and publishing after he left and has no say anymore."
Except for some reason Kamiya is still allowed to "expand" a series he has no say in ever since the second game came out? No, he doesn't. He has about as much say in what happens as Bingo did for DMC4 in his novel.
Kamiya's idea was that Vergil was kidnapped when Eva was killed (hence, Dante "lost a mother and brother to evil twenty years ago"). The novel outright ignores just when Dante is supposed to meet Vergil after the fact, and has him understandably not recognize the guy due to bandages, only to later not recognize the guy even though he bares his face for the entirety of the last battle, and he doesn't recall the events in the novel whatsoever. DMC4 states that Vergil as Nelo Angelo was already dead, but that his death took place when he encountered Mundus at the end of DMC3 in which his body was destroyed and his soul put into a demonic construct. Gilver is not a demonic construct.
Here's what the files in each game say for Ebony and Ivory:
Devil May Cry, Guns — Ebony & Ivory: "Dante's
hand-made guns."
Devil May Cry 2, Weapon File — Handguns: "Dante’s
hand-made twin pistols. They fire bullets with magic power."
Devil May Cry 3: Dante's Awakening, Guns File — Ebony & Ivory: "Dante's
personally designed handguns made for rapid fire action."
Devil May Cry 4, Dante's Arms File — Ebony & Ivory: "
Personally designed by Dante, these pistols are the weapons of choice when rapid-fire is a necessity."
The novel contradicts this simple fact: Dante made the guns himself. Someone else did not make them for him, he did not merely
assemble them himself, he built them on his own and customized them as he needed. The second novel is also wrong about that.
Abigail was explicitly stated to have power that rivaled Mundus, the only Demon King mentioned thus far, and even if it wasn't Mundus and he rivaled Sparda or Argosax or whoever, that doesn't excuse Dante beating him with a one-second DT and no Sparda sword. The anime does not give a flying crap about the game it's set after. The specific quirk of Dante eating sundaes and whatever else does not make the novel "entirely" canon, simply whatever its referencing. For all intents and purposes the anime is the "official" debut of the various quirks. And again you completely ignored what I said; they never state that Dante is 'Tony Redgrave', simply that he is 'Tony', last name unknown. Never said, never clarified, as you say.
A retcon by its nature discounts the events that it's taking the place of in the order that it happened in, in order to fit whatever the writers want. You may not want to, but the writers did anyway.
I don't care about your point about reboots. I am not one of the people you'd best be making that point to. Take it up with someone who actually
does bitch about DmC not fitting in with continuity and "wah wah NT ruined the canon".
Not caring about continuity or consistency is what
causes retcons. The best retcon is actually a "revision" which doesn't majorly contradict events and expands the universe without raising more questions about what happened or reshape events to fit demand. "Japanese writing" is
all over the previous games, hence why DMC3 seems to not care about the legend of Sparda when it's centered around the legend of Sparda (among other things). You're basically saying "the Japanese don't do retcons, they just don't recognize when the writing doesn't match up and fail to acknowledge that their plot is a mess", which is the least flattering point to make about the difference between Eastern and Western plots. If you're gonna say the Japanese are incompetent, just say so.
Re: Kamiya's quote: Wow. So he says that "You the fans are truly what decides the fate of the series so whatever you believe so be it. That being said no matter what we the creators say in the matter will not change your view", yet a page before you said that "the communities ideals are not part of the series, only the creators and those who work along side the creators decide what is part of it and what is not"? Talk about convenient. Either you go with Kamiya accepting that fans believe what they want (and you should too), or you don't. Pick one.