Most people probably didn't notice, but enough people picked up on it and are praising EXO for this small detail.
In their winter album 'Universe,' their songs don't talk about girls or boys, they only use the words "you" or "i."
Have you ever had a song that has romantic lyrics about a girl and you change the word to 'boy' or vice versa? What if you are someone that doesn't identify as either gender? The list of reasons why this is moving goes on and on.
Basically, anyone can connect with these songs because they are about loving someone, but they didnt put a gender on it.
Props to SM, EXO, and their songwriters!