While I agree with your point that it should be perfectly acceptable to not invest oneself fully in getting the best performance in a job as long as you can do the job you are hired for, I think you are mistaking OP's statement for an absolute one: these are from an opinion piece on a personal blog, and the arguments they bring up resonate with them.

Nowhere did I see any judgement for those who don't agree with them: they merely proclaim what you can easily achieve with deliberate observation and practice and how it matters to them.