diaglo
Adventurer
Those player and DM roles haven't really changed much in 30 years. One can put on the viking hat running 4E as easily as one can hand the reigns to the PCs in 1E, and vice versa. Perhaps more tellingly, and ultimately more illustrative of the point, no matter what the edition, it is the players that ask the DM "What do we see?" and the DM that, upon responding, asks, "What do you do?"
i am not trying to disagree, but i think this is part of Fenes said already.
the referee and players' roles have changed over the editions.
it really depends on if you use the rules as guidelines.
part of this is party size.
cutting back on the hirelings, henchmen, and camp followers.
and cutting back on the number of players. 20 is no longer optimal.

which means you don't need a caller for the group. players can act as callers for their own PC.
but it also means that combat gets a bit more hectic. if the group isn't on the same page with tactics.