As someone working predominantly on React sites for the last 4 years or so I absolutely agree. Of course you can write quick, responsive and solid sites with React but it’s not the automatic process some would like you to believe, you still have to try and often the effort required is not trivial. The problem I often find is that optimising React sites needs a bunch of knowledge and skills which are only tangentially and most related to those which you’d use to optimise a more traditional site. This is related to the topic of the OP i think; knowing how to write good css is a skill which css-in-js tries to pretend doesn’t matter but which absolutely does - things like Styled Components effectively enforce certain good practices but don’t remove the need to understand whats going on under the hood in all but the most basic of situations.