It’s just bullshit sexism in play. It’s those people forgot (or don’t even know, because they’re just buying into hearsay) that John and Paul started to dislike each other long before John even met Yoko.
Yeah, not to mention that George had been drifting away from the band for years, and Ringo was feeling underappreciated to the point where he quit the band during the production of the White Album and only came back because the rest of the band begged him to. Neither of those things had anything to do with Yoko at all. Add to that the fact that Brian Epstein died, requiring the Beatles to become business partners in addition to their already stressful creative partnership, and it was a recipe for a breakdown.
Yoko was an annoyance for the rest of the band, but to say that she was in any way responsible for the band’s demise, much less solely responsible, is fucking ridiculous and ignorant.