He was a great player but the team signs a player based on its current status.
We cannot forget his contribution to the USA basketball as he also lead in winning in the international tournament like FIBA and olympics IIRC.
That's why veterans like to help him because of his status and contribution in the past, but team are getting a player based on what he can offer to the team, this is just purely business and nothing is personal here.
We will never forget the contributions of Melo and on how great he is as a player and being a superstar. Still no clear reasons why most of the teams aren't signing but I'm still hoping for his good fortune that there will be a last minute contract signing.