Why is the dividing line of evilness and alcohol such an abstruse and abstract force?

No can't see alcohol unless taken in large amounts as causing evil. Then it chemically alters us.  By dissolving inhibitions it can allow us to do things we would not have done without it but if those things are "evil" they were just in us to begin with.  And we are allowing the alcohol to bring them out. 

Because not all drunks are fighting drunks. And some people are so combative they even fight without being drunk.

I never heard that history's greatest "evil" villains were alcoholics.

not sure why