Party leader only is bad

Sometimes it's nice to have multiple people being respondsible for their own signals:

Tank: focus on this target first.
Blm: I slept this mob, leave it alone.
Random party member: I need a heal!

Now in in small party, attacking a few mobs, it's still manageable by one person. But in bigger raids with complex strategies and/or a large amount of mobs (we are getting those right?!...) , that shouldn't all fall down to one person.