huh? that's not how it works. Possession is a whole inflection in english. His, Hers, Theirs, Mine, etc. The 's thing is an abbreviation bc that's how every single language on earth works, they tend to have abbreviated forms of words and expressions. With all the valid criticisms you could've given (inconsistent spelling being a big one) this one just ain't it, chief.

I hate it when natives pretend that their language is "hard". It seems like a common attitude around the world. Native speakers are unable to objectively (if that was even a thing) discern how hard or easy their language is.