This was covered before, in similar posts to this one:
The DHC in the OP completely concocted that "four guys allowed out of the dugout" statement. There is no such rule, whether permission or prohibition.
As I've expressed, this ploy is done by travel-ball / academy teams especially. I'm of the opinion (and many other umpires here are too) that two – the (upcoming) batter and the on-deck batter – are all that are needed and should be allowed. If I'm at an elite tournament, and both teams are doing it, I'll be a bit more lax on how many are out (if I'm at a Perfect Game Tournament, for example, and Perfect Game is paying my check, and there is a PG Field Marshal present, I'm not going to ruffle coach feathers by telling them how many of his guys are allowed out or not), but I will heavily suggest / request that helmets be on heads while doing so. CDP strongly encourages (and most umpires enforce) only 2 out of the dugout.
As @johnnyg08 and @scrounge expressed, Fed rules outline where out of the dugout activity between innings should be confined to, and which players are allowed (by role). This is done, obviously, for safety. An alternate and supplemental reason, though, is to reduce intimidation. I was a catcher for 16 years, I know why these kids do this! I know why they stand as close to the "dirt circle" (some fields have so little grass, you can count the blades on 1 hand) as they can before some sane adult tells them to stand somewhere else. They don't need to stand there to get a better look at the warmup pitches! They are standing there so as to indicate to the pitcher, "Oh yeah man, I'm not scared of you. That's my plate. I've got you figured out."
11U? Stick the little urchins in the dugout – both teams – and tell 'em it's 2 out, with helmets on, and if any adult protests, just say, "Nope, we're going to be safe about this."