My point was that you need a better reason than 'It's metagamey' to justify hidden information, when the information you expose is equally as 'metagamey.'
'It's not RAW' doesn't even apply; the DMG suggests that you play your encounters as an open book. That much information should be made available, and that hidden information should be things that are -actual- hidden items. Traps are hidden. A brute is generally not.
So, as I said... you need a reason for hidden information other than "I don't like minions" and "I don't like monster knowledge checks" and "I don't like the suggestions given to me by the DMG or the designers of the game itself" in order to justify it.
"It's metagamey" does not fly in 4th.
Sure it does. That poster asked why some people think it is metagamey and I gave him the reason. It's information beyond what the PHB indicates and the DMG suggests handing out as RAW.
Metagamey is when the players make decisions based on game mechanics information that the PC and hence player should not have. Players should not have information about role until actions by the NPCs illustrate that information IF EVER. The DMG does not suggest that you play your encounters as an open book.
Is the enemy leader a "Leader"? How would you as a player or your PC know?
Is the enemy leader a "Controller"? How would you as a player or your PC know?
Just because an NPC uses a power that Stuns does not make that NPC a Controller. Most Dragons are not Controllers, but most of them Stun.
Just because an NPC fights the PCs by itself does not necessarily make it a Solo either.
Just because an NPC is big and strong does not necessarily make it a Brute. It could be a Soldier.
There are lines in the sand and each DM/group make their own.
When one gives out game mechanics information to the players that the PCs should know nothing about, then one is playing the mechanics and not roleplaying the game. That's metagamey.
You can call it anything you want.
A certain amount of this is inevitable, but handing such game mechanics information out is not suggested by the DMG. It never once mentions handing out game mechanics information like AC or role.
It suggests that you hand out information that the players need to know, not information that the players want to know.
Therefore, within the rules of the game and the limits of PC knowledge, Insight, and Perception, tell players everything they need to know.
Roles are something the players do not need to know. In fact, a player could play the game for years without ever knowing that monster roles even exist.
Now, there is an argument that minions can create a gotcha situation, but that argument isn't very strong. Minions are lame, the only gotcha a player can run into with them is to hit them with too strong of an attack and that doesn't directly harm the PCs (and can even end the encounter quickly).
The gotcha section in the DMG says nothing about running encounters like an open book. Minions do not change the basic tactics of combat. You still need to damage them.
Information about monster condition (daze, stun), bloodied, is using an aura, sure. Information that the monster has 1 hit point or twice as many hit points as normal, no.
It's a slippery slope to hand out role information because it leads to "Oh, that's a Lurker, I should hit him with a Will attack" and the game disintegrates into an optimization exercise.
The bottom line is that even the DMG suggestions are overly generous. Players shouldn't know stuff that their PCs cannot detect or do not know via knowledge. As an example, traps. The DMG goes through a song and dance about giving information out about hazards and obstacles which is fine, but includes traps in that paragraph. That's fine as long as the trap is observable. But some traps, like those designed by intelligent foes, should be difficult to observe as traps. If the PC makes the high DC Perception roll, great. You see something amiss. But traps are not hazards or obstacles. If it is a designed trap, it should be difficult to spot. If it is an accidental trap, then it's really a hazard and the difficulty should be based on what type of hazard it is.
But this idea that the players will not be having fun if they do not have all of the information for a given situation is bogus and flies in the face of some of the reasons why some people play the game in the first place.