What is a hubless electric motor?
They're essentially a linear motor wrapped into a circle.
You want hubless motors and (hollow shaft motors , and hollow shaft encoders, for that matter) when you need or want to have something else occupy the space where the hub would be.
Many times the center of the axis of rotation in an instrument or machine is a prime spot with many contenders vying for a chance to sit in there.
Edit: Based on your newly supplied link, I'm not sure that is an accurate description of the motor. Most of the similar products are called &quot;unit bearing motors&quot; and are shaded-pole fan motors with an integral sealed bearing arrangement.
For example this one.