About game balance and complaining

Judging from the various complaints regarding the changes in the patches, why do I get the impression that there's quite a dissonance between what is imbalanced to the players and what the devs nerfs and buffs? Where do they base the changes anyway? Are the complaints valid? If it is, then who is the target audience of the changes? Or are those complaints coming from salt? I'm not a competitive player, so I have no idea what to think.