Not required, but I’ve been doing them since the early 90s. I mainly hate when I get a mix and then have to run it round the stores asking “what is this?”
I’ve seen some who claim they don’t want other DJs “stealing their playlists”, but I respond that if they need to hide what they play then it shows they don’t have anything unique to offer that sets them apart from other DJs.
In the long run, more exposure for the artists means they make more money in sales, and this equates to them producing more music you like…as opposed to quitting and leaving behind a plethora of mediocre and bad producers who make crap.