sendfrom needs the minconf to know if it should fail because of too few confirmed coins in the account.
move used to need minconf for essentially the same reason, but as of (some release in the past) it always succeeds.
E.g. if account A has 5 0-confirmation bitcoins and 5 1-confirmation bitcoins then:
move "A" "B" 10
... used to fail, because A's 1-confirmation balance was only 5.
Now it will succeed, giving it a -5 one-confirmation balance. move "A" "B" 100 will also now always succeed, making A's balance go negative.