I'm glad to hear that. As for why, well, fandom wikis seem to do that a lot.
The Evil Dead wiki doesn't consider the fourth or fifth films canon despite confirmation from Sam Raimi, Bruce Cambell, Lee Cronin and Fede Álvarez that they take place in the same universe. They confirmed that the different books are the trap copies from Army of Darkness.
The Exorcist wiki claims that only the first and third films are canon, Dominion and the TV series is semi-canon (which is certainly the least canon instalment after Believer even though I'm still covering it), and II, The Beginning, and Legion VR (despite being about different characters and not adapting Legion) are non-canon. Now, the continuity of that franchise is weird, but Green confirmed that The Exorcist: Believer wasn't erasing any of the other films canon-wize. The third film literally avoids showing the original house so that it doesn't contradict the second film.
I'm sure there's other examples.
If there's no source, it's likely just someone making it up and rationalising it. "It's a comic book, therefore non-canon" energy.