Well root motion is the future but coders like in place using the movement component while animators love root motion as it keeps the player grounded. If you wish you could use RM and can replicate but the movement component handles a lot more that you would have to more or less build from scratch using RM.
Until there is a networked “root motion” component as there is a in place movement component it’s a risk at least our/my coders are not willing to take.
P.S. Epic has yet to state “anything” as to networking with root motion.