Many people don’t even realize that it’s disputed usage, and it’s not historically wrong: “Alright” started life in Middle English as one word and split soon after, though “all right” fell from use for quite some time.
Among the interesting things that Perlman points out:
Nowadays, in polite company “alright” appears most frequently in quotations. That’s a curious distinction, because no one spells what is being spoken, and “all right” and “alright” are pronounced the same, not like “going to” and “gonna,” another dialogue inhabitant.
Perlman writes that most modern style guides say not to use it. And some people can't stand it, such as author John Scalzi. He wrote on his Whatever blog in April:
“Alright” is an abomination against all things good and pure and those who use it are on the side of the demons.