That's probably because it's made up of almost entirely veteran players. If you examine the Lucky Bancho data, it is actually almost entirely alts and veteran players that went over. This is even clear if you look at the evidence of boosts bought on it (you can see by this massive spike of people at level 80 that barely exists elsewhere in the data). Veteran players are more likely to be impatient because they already know how to do everything efficiently, and that can come across as toxicity.
I was on Crystal for a very long time. It was the nicest people ever, because most of the ones with attitudes transferred over to Aether because it was the raid DC. It left mostly people who were nice enough to stay behind and teach sprouts, and sprouts who were nice due to how new they were to the game. It reflected this in the higher-end duties as well as they completed the MSQ.so idk.. heard same for crytal and aether..
On Aether I don't see it at all either, so this sprout effect even happened to Aether. I've not seen any of these awful things you described said in any dungeon, trial, frontline, alliance raid, hunt train, extreme and savage prog, farm or reclear parties, at all.
I do the alliance raid every week, I do expert on many days of the week, I have grinded all the series rewards from PvP every patch (the last few patches through Frontline), I have done an amount of hunts that I have the victor mount and almost the 10k A rank achievement and I've seen nothing like you described.
Yet, my few, rare visits to the EU region I have seen the behaviour you described. Just casually going into an Expert roulette, people have treated an average returning player so poorly that it has made me uncomfortable and I've seen insults hurled at people just doing the trial and raid roulettes. There are people in the EU region who are far more blunt with their words and unaware of the rules it seems like to me.