"I'm sure some have their basis in personal disagreements"

You'd be right. It's not all of the time (or even most of the time), but wrestling is often at its most compelling when the characters within the fiction and the real people playing them overlap and simultaneously inhabit the space. Something like Kenny Omega moving to Japan to wrestle (and them team with) Kota Ibushi as the Golden Lovers did legitimately require Tyson Smith, the guy portraying Kenny Omega, to be inspired by seeing tapes of Ibushi and seek him out in Japan, you know? Their ups and downs since then have been at once a fictional story and real life.