Signing up for an Endgame Shell: "You MUST have all classes to 50 even DoH/DoL."
Signing up for an Endgame Shell: "You MUST use Teamspeak/Vent/Mumble."
Shouting for Primals: "<Primal> <Do you need it?> 1/8, BLM, BRD, WHM and Tank Please."
Shouting for CC SB: "BLMs and BRDs only please."
Shouting for Regular SB parties: "BLMs, BRD, WHM and WARs please."
Shouting for Dungeons: "BLMs, BRDs, WHM and Tank (WAR) please."

So what's the difference with Japanese players shouting for others who can speak Japanese and what pretty much everyone else does? Showing a preference? It's about communication even in regular parties, so those who say "You don't need to talk in x" just because you choose to be anti-social doesn't mean everyone else view that belief.