If a bunch of people got up in arms and started complaining because the author of said CSS example hadn't considered that their code could be changed slightly to produce a hate symbol, I'd definitely still jump in and say "but that's not what they were doing!"

The original claim was "technique proposed would in most cases be useless"

Technique does not mean precisely what the person was doing just their method. Their technique has very obvious applications to user tracking.

People have abused it (e.g. https://arxiv.org/pdf/1810.07304 ) and then it was changed to make it more difficult to abuse.

Ignoring risks do not make them go away, it just makes it easier for bad people to exploit them.