Most random character generators are dice with a vocabulary. They roll a name, an age, a job, a flaw and a quirk, and print them in a box. That is a good start if you play tabletop games or you are stuck on a blank page, and it is exactly as far as those tools go: a line of text you still have to turn into a person.
The next step is the hard one. A face has to exist. The same face has to exist again in a different room, in different light, a week later. A written description does not hold that on its own; two generations of "a tall woman in her forties with grey-streaked hair" are two different women. This is why people who write stories with generated characters end up with a folder of images that do not match.
Reelfo starts from the other end. The character is a profile that a story needs, a sheet drawn from that profile, and an image that travels with the character into every shot. "Random" here means the parts you did not decide are decided for you, in a way that fits the rest of the story.