It maybe was more legitimate when all ale brewers always skimmed from the top (if ever that was the case,) and lager brewers then may have been the only ones exclusively harvesting the settled yeast. But since the 19th century, ale brewers have selected yeasts that behave like those lager yeasts, settling quickly, first so they could sell bright cask ale without having to age it, and even more so when ale and lager brewers alike started all using the same conical fermenters. And of course we all know now the genetics show that there is overlap in species, some traditional ale-making yeasts being pastorianus and some traditional lager-making yeasts cerevisiae. So it's all pretty meaningless, and I will propose again my own provisional method of defining ale and lager, the "quacks like a duck" method. If it smells like a lager, and tastes like a lager... you get the idea. Who cares what the yeast is called, or what it is. What qualities can you get in a beer you make with it?