No one sucked the lives out of tennis players more than Borg, and he was idolized. This goes WAY beyond style of play.That's "one" reason why some don't like him.
The main reason is because he plays BORING tennis. He does not give anything to a normal fan to get excited about. It's all about sucking the life out of an opponent without going for any sort of winners. The "Sinners" or "Alcarazes" or "Shapovalovs" or "Tsitsipases" attact more fans because of their exciting brand of fearless and explosive tennis. Medvedev is another boring player or will become one when he's on top.
Zv is slightly more exciting than Med because he has weapons. Another example is FAA. He's another boring player. People don't like robotic play. That's the truth.