Picture it: "I'm gon' make you folks remember me," a melodious voice says over the radio. "Sounds good, Future," you think.
The Future/Rich Homie Quan similarity is such a strange thing, like a momentary ripple in the space-time continuum, a glitch in the matrix. There is something different about the two of them, despite the evident similarities. It's difficult to put your finger on. Quan himself has said, in his defense, that he can't help how his voice sounds, so he'll just talk about his own story, which no one else has. And it's what makes a track like this seem so moving. His story isn't unheard of, but he presents it in a novel way, less oblique than Future, more autobiographical and specific.
Another theory as to why he's stood out: Everyone is emulating Future, while trying to sound like they're not. Quan has differentiated himself from the pack by sounding slightly more like Future than anyone else. But these are his memories, of course—no one else's. So he can get away with it.