It's still really hard for Japanese players to break the misconsepsion that all English speaking players are terrible

I'm sure most of us should know it is because of the difference in culture and stereotypes, English speaking players are more open to accept other kinds of players while Japanese players tend to like to keep to themselves. Japanese players tend to give more notice before needing to leave a party while non-Japanese players give short to no notice at all about leaving etc...

But it's usually is because of the language barrier and because the auto-translate on JP client is not very good ( I have been playing since Japanese release and play on JP client and know first hand that the translations are not very accurate so I can understand )  Also many Japanese players either cannot read romaji or find it difficult/stressful to sound it out from English

I'm sure it's not really about being racist but they just don't want to learn English. Not all JP players disllke NA's!  I've been in more NA linkshells than JP linkshells because the atmosphere fits me, I like being casual and not tied down, which is hard to find in Japanese culture