Account buddy system and can you opt out?

no the ppl who add you as account buddy dont know your account id. when you account buddy someone the characters ign that they were on at the time will be the blue name you see which signals that they are an account buddy.

for someone to be an account buddy they alrdy need to be on your buddy list and need to accept your account buddy invite.

also only account buddy ppl that you are really close with.