I remember not long ago I got some confused looks from others for not using the "copy to clipboard" buttons that some sites (which I did trust enough to allow JS on) have around code blocks and the like. They were just as confused why I was not using that "useful feature" as I was why they didn't seem to realise that selection is a built-in feature of the browser that behaves (mostly) predictably and is available everywhere. I'd rather select the text myself than click a button that claims to do it for me.