Nobody is saying you dont get 4 grams for the price of an 8th, they are saying (and they're right) that you cant get a 4 gram 8th because the math doesnt work out...

simply put, you buy 4 grams, not an 8th. as a technicality you really cant call 4 grams an 8th though, no matter how long you've been buying 4 gram "8ths"...

BUT, to stay on topic, here's a pic of a quarter ounce, 7 grams.