about: L2 VPN over MPLS

hi,

    i have some doubts about when we implement L2 VPN over MPLS we SHOULD keep 
loop free. See draft-lasserre-tls-mpls-00.txt. why?

    why not just use such a simple algorithm described below? 

    1. if the L2 frames are received from a interface connecting to a CE, 
forward the frames to all other local interfaces in the same VPN, and also to 
all other remote PEs which sites within the same VPN are connecting to.

    2. if the L2 frames are received from other PE, just forward the frames to 
all local interfaces in the same VPN with the frame.

    is it like the full mesh topology for the IBGP peers?

    and what will happen, if protocol operations in this way?

    thanks.