Because for fans of the genre of rap you are describing, the misogyny is part of the appeal, part of the brand. Along with guns, drugs, etc. It stems from 90s gangster rap, which in its purest form described the life experiences of individuals who grew up in crime riddled, impoverished inner city areas where these themes were prevalent in every day life. In the late 90s/ early 00s the music began to glamorize the lifestyle and this is the stuff todays rappers grew up listening to.

That is all to say, the people who this music speaks to most are not the type to call for the “cancellation” over socially inappropriate lyrical content.

On the other hand, fans of John Meyer tend to shade a little more on the suburban side of society. This demographic is more likely to be socially liberal or at least present as such and therefore the artists they listen to will face more scrutiny.

You don’t have to look far to find people calling out rap for its lyrics. That’s been happening since rap existed. Those people don’t listen to rap, though.

TLDR: “career ending” cancellations only happen when the people doing the boycotting are the same people spending money on the music.