Doesn't. The claims of a genetic bottleneck hasn't panned out, and obviously, with a crowded SE Asia, it wouldn't do very well, would it? ;^) The eruption of Toba is now known to have had basically no impact on India, for example, where humans already lived, and continued to thrive.
“The claims of a genetic bottleneck hasn’t panned out”
Well, I’ll be derned. I totally missed that change.