In fairness, this might have just been an overly-broad solution to a certain problem. That is, if you have an element that is clickable and isn't an <a> or <but

In fairness, this might have just been an overly-broad solution to a certain problem. That is, if you have an element that is clickable and isn't an <a> or <button>, double clicking it can cause page content to be selected when this was not intended. "user-select" should be disabled more specifically than it is in this case, for sure, but that is what I suspect is really going on here.