What you are proposing is not technically feasible. Wikipedia learned very early that banning sock puppets based on IPs just does not work. AOL for example mixing up all of its users in the same IP pool, multiple users in different houses will post from the same IP. What is more anyone with a whit of sense can bypass such blocks using TOR or VPNs or even just a web based anonomizer if they are not technical.

It is an endless game of whack-a-mole with no winners and plenty of innocent losers. Best to just judge people on the content of their arguments instead of some concept of identity.

Identity as a basis for trust is over rated.