Why is r/mapporn so racist?

I've know that r/mapporn isn't the best subreddit for a while but I checked it out before and holy... One post was showing the percentages of Muslims in each European country and the amount of racism in the comments is horrific. People calling for 'drastic measures ' and a loss of 'culture' when the numbers were between 0.1-10 % at most.

Of all subreddits you would avoid I wouldn't have thought it would be one about posting maps, why is it such a bad subreddit?