I knew a lady that all she did was FMQ on her long arm, and had way more business than she wanted. But she'd built up a reputation of doing very nice work, and since she was doing it in her retirement years, was also very competitive. She also did what she wanted to do on a quilt, the customer didn't decide. I'm not sure how it would work out doing it any other way, as there is just too much variable with FMQ.
I have a computerized system, and really like the simplicity, though I do want to do more FMQ now that I'm retired. But for most quilts, I really like being able to get it on and off the frame in less than a day.