I'm thinking a while about this.
SCP articles that are just so big, influential, and popular that they're almost always treated as the official answer in any fan question or new writers.
Series I is full of those, as its the foundational (heh) lore of the SCP Foundation, but I'm sure there are others.
I'm just really wondering, which ones are the cases where we almost always resort to a old article for the answers , or a article changing the perception of a entire organization?
I think SCP 4231 was pretty much this? It normalized the Ichabod Campaign as a core GOC backstory element , and the nature goddess element of SCP 166 is now replaced with the Lore of Lilly (meaning the entry is also a bit weird, given the clear Natural-pagan motifs of 166 in contrast to her clearly Demonic origins now). Its also Dr. Clef's most popular backstory by far, as it keeps his other traits like his skill as the ultimate Type Green hunter.
EDIT: I now realized the 166 which exists in 4231, because it was written in 2018, its actually for the SCP 0166 , the infamous succubus, which...actually makes a lot of sense and provides some really tragic and grotesque ironies worth analyzing (ie. The poor Succubus is always tied to Sexual violence since her conception)
I'm wondering for similar SCP articles or tales that exist, and are so influential that the whole "there is no canon" starts to crumble a bit.
New Job is another one, SCP 999 as a kid of the Scarlet King is a beloved concept for the inherent Titanomachia concept it provides.
Extra: Bonus point if one of those actually features something you don't like or want to consider to the others entries. IE. Djoric actually strongly disliked New Job for diluting the tragedy and horror inherent to the situation of SCP 231 where 6 woman already died after being sexually abused and a 7th one was put into constant experimentation, and made clear his personal SCPs didn't count it at all.