I guess not

.
Originally the Skaven army was designed with the rule that they could not advance after destroying an enemy - only if they destroyed him in the first round of combat.
Later on someone decided to leave that rule away obviously not being aware that there is a "rat-tail" of other things linked with that rule. That's probably the army list you got to know.
Leaving that rule away changed the balance of Skaven a lot imo.
Greetings,
Gerald