They came and they heard Him preach, and in this case, they came and got bread and fish. They even saw miracles - miracles of healing, miracles of exorcism, and in this case, the miracle of the multiplication of the food. But when sundown came, generally they went away. But the disciples, they stayed and, as ornery as they were, and as difficult as they were in many ways, after Jesus' Resurrection, His command to the church is. Go ye into the world, preach the gospel, baptize, and make disciples of all nations.
Disciples are a lot more trouble to the master than just people.
Those folks who just showed up to hear Him preach and then went away, probably learned something. There's no question about it. It probably changed their lives in some way. I'm certainly willing to believe it made a huge difference to them. But still, they weren't disciples.