With VPLS one need not flood multicast traffic to every egress PE
as long as you do IGMP/PIM snooping on the PEs.
Even with IGMP/PIM snooping in VPLS, how do you propose to limit the number
of PEs in a given VPLS instance. We should keep in mind that a VPLS
instance constitutes a single broadcast domain among all the PEs in that VPN.