For Variables it's normal to do a Create Variable action and directly assign some value.
For lists, however, it is required to create the list in an extra step.
This is most annoying in cases where you need to work with a list (e.g. in generic methods), but actually only have a single object -- e.g. workflow assignment microflows require a list return value while tasks are often assigned to a single user; so you need to create an intermediate list... in two steps.
It would be a nice feature, if it was possible to integrate the changing of a list directly into the list create activity.