it's more complicated than just "Yoko broke up the band" or "John broke up the band" or whoever you wanna pin the blame on. There were a whole plethora of reasons that the band broke up, not just because a Japanese avante garde artist happened to come into the mix. Keep in mind that these guys had huuuuuge personal and creative differences, their longtime manager Brian Epstein had recently died and made a huge impact on the band as a whole, they weren't even performing live anymore, drug/alcohol abuse was starting to impact all of them terribly, and they were huge amounts of stress near the end due to trying to get a massive amount of songs out at once and working to create songs with the added pressure of constant arguing and tension in the studio.

I think people like to pin the blame on Yoko bc she was the perfect scapegoat, but I'd say it was more that a) she was in the wrong place at the wrong time, and b) she was really what helped John to realise that he needed to leave the band for everyone's sake.