To build on what others have said. Multiple motors per axle allow you to get rid of the diff, and you get torque vectoring basically for free.

Then there's braking. More driven wheels means more braking energy that can be recouped via regen. In traditionally rwd cars you lose out here because braking energy tends to be directed forward.

Also there's packaging. One large motor might impinge on the cabin.

Also you get benefits wrt mass production.

A smaller motor is easier to handle. Potentially could avoid the need for high voltage cables. Which eases repair.