IMO essentially ML experts don't work in a bubble and may interface with potentially anyone at a company; C-level, engineering, product, marketing, ops, etc etc. What other tech-employee needs that flexibility? So, I grouped communication / life skills into being able to understand, read, interpret and ultimately provide value to potentially any team. Just having the technical skills will only get you so far.

Isn't this part of what most software engineering degrees teach though? Particularly surrounding project planning and requirements gathering?

I might be an outlier, but I interface with all of those on a daily basis in my role as a software engineer

IMO software engineering experts (leaders) need to do the same thing.