Skills have to be maintained. You don't remember everything for life. I highly doubt anyone that uses a calculator on a regular basis was never taught how to do math by hand. I was taught of course, I'm not only old but I went to university, but I would still need refreshers to really do anything of any complexity.

I don't think it's a vacuous argument, it's just reality. I can use a calculator as long as one is available, but if I'm lost in the woods, I'm still going to need a refresher because calculators are too plentiful to maintain advanced math skills.