Now you’re confusing the nature of it. It’s like comparing LFR in retail to the many PUG raids in Classic.
In the PUG raids, many people talk. In LFR, many people don’t. You know why?
It’s partly because of the difficulty of the content in LFR being easy to the point of afking, but it’s also because of social mechanisms like the act of reciprocation and internally accepting each other.
^ This is an example of what the act of acceptance can do. It leads to more implicit trust just from the act of grouping up together, while if the part of grouping up would be automatic then there wouldn’t be any of that implicit trust forming because you’ve yet to accept each other then.
The fact that you’re also on the same server, even in those PUG raids, means people are more aware of the social aspect than they are in LFR. Because in retail and LFR, you can act as bad as you want and it still wouldn’t really impede your ability to do stuff in the game.
But when you behave that bad in Classic with everyone from the same realm, there are actual consequences to it. It will impede your ability to do stuff in the game like that.
So this, and also other things, serves to motivate people on a fundamental level, to work together and be generally constructive. Instead of not caring about anything and being apathetic about it, which dulls the immersion in the content itself.
Doing this repeatedly, seeing the same people over and over again which you can easily remember, leads to effects like these happening naturally:
Compared to the many names you’ve already forgotten from the xrealm matchmaking, and never bothered communicating with for the sake of better teamwork.
(It’s not like I’m saying you’ve never communicated like that in the xrealm matchmaking, but when it occurs it tends to be with only a select few from an entire team of players you’re also playing with, and you’re highly unlikely to have bothered remembering anyone of them if you’ve done a lot of BGs anyway.
Not to mention the ones that never reciprocated, or in other words they never said a thing back to you, those you’re even more unlikely to have bothered remembering the names of.)