It'll make more sense if you throw words like "objective" and "subjective" out the window. Anyone is free to give their reading of--or make an argument about--a work. Some arguments are simply better than others.
if you share similar opinions i guess it helps people find more music they may like, also people like to feel validated so they like to read what other people have to say about things
there isn't much of one tbh, but for some people it's entertaining, especially those who don't agree with music being subjective
