A lot of people have explained how that would happen, in excruciating detail. The reason why this wasn't a major part of the discourse is that most people (including myself) did not believe jumps in capabilities like those we have seen in the last few years were likely.

For a superintelligent AI trained with methods anywhere close to what we are doing now, killing all humans is the default outcome. I actually think researchers are downplaying the risks to make their arguments more normie-friendly.