Probably because when you were a baby you put everything in your mouth, so the data bank is large

From your own source:

“When should you not use a possessive apostrophe? Do not use possessive apostrophes with pronouns, which have their own unique possessive forms.”

You wouldn’t use he’s or she’s or they’s for possession. It goes: his, hers, theirs, its. The cat’s knees = its knees.

its*

(It’s is it is)

“Its knees work hard because it’s severely overweight.”