Luke probably was acquainted with him and so mentions him specifically. He may have continued to follow the Lord and even been among the 120 later, whereas the other may not have.
At any rate Luke doesn't say that the blind man was alone, just that he was there and received his sight.
Asking questions is very important. It helps us learn, understand, and connect with others. We must continuously question ourselves and others to verify we are on the correct path.