if you’re a professional in any field, it is inappropriate & bad business in nearly all circumstances to publicly criticize and weigh in on the work of your colleagues. The entire process of doing so creates an abundance of potential conflicts of interest. (Imagine you publicly criticized a co-worker at your job by calling out his performance and bad mouthing him on the internet. You would most likely be reprimanded or fired.)
I’m sure Lebron James was a basketball fan first, but he is a player now. He doesn’t spend his spare time publicly offering opinion and criticizing the work of other pros. He works on HIS game. If he is asked about a colleague, he is complimentary and will recuse himself from offering further opinion. One only needs to look at Terrell Owens to see an example of the opposite behavior and its resulting silliness.
Publicly weighing in on the work of others is for journalists and fans. Recording artists who engage in this behavior do so because they see themselves as amateurs on the outside looking in and cannot appreciate the importance of class and professional etiquette. Until one learns to behave and see oneself as a pro, he cannot expect others to see him as such. Everyone is entitled to their opinions of others, but pros know it’s best to keep them private, shut up and let their work do most of the talking.