It's a really common misconception among technical folks that "subjective" == "arbitrary".
Design is inherently subjective, yes. But that does not mean that all design choices are equally good when goodness is measured by pleasing the greatest quantity of users by the greatest amount.
Ice cream flavor preference is subjective too, but if your ice cream shop only sells "sawdust sprinkles" and "frog's blood", business isn't going to go well for you. Or, perhaps closer to home, the choice of keywords in a programming language is entirely subjective. The compiler does not care if you use "while" or "rkdhx" for loops, but good luck convincing programmers to adopt a language that chooses the latter.
Designers have laboriously learned the aesthetic principles that align with how our visual system works and with the expectations users have coming from our shared culture's graphic history. That's what they mean when they say something is "right" or "wrong", and they have a lot of expertise to back it up.
i also kind of feel like your comments distill down to something very close to:
"there's no right way to do it, but that way is wrong"
design is inherently subjective. no single tool will seem "right" to everyone, and that's ok.