It has the implications of "all people of a certain common history being are all the same way", which is still discrimination, even if it's not blatantly racist.
I was making fun of the caption which jokingly said that "americans deserved 9/11" with a cursed image (imgflip.com/i/8h44zt). I don't have a problem with people who practice Islam, it was a joke.
Let me explain to onlookers of this interaction that what I meant by it's "not blatantly racist" is that Islamic people come from many different races.