Chard is just a rootless sub-species of beet, which is the reason the leaves are so similar. In some countries chard is even called "silverbeet".
I first observed chard in my youth, when a neighbor several houses down was growing it. He grew
trophy chard, leaves as large as rhubarb... although I never ate chard as a child, it left a lasting impression. So did the first variety I grew - and it was not a favorable impression. Lucullus has huge leaves; but they are deeply ruffled, and offer good hiding places for things you
don't want in your food. Even after washing thoroughly, there would still be slugs, bugs, and spiders crawling out. After two years, I became so disgusted with the "cling ons" that I stopped growing chard for quite a few years. Only after I found smooth-leaved varieties did I begin to grow it again.
@digitS' , Verde de Taglio does look interesting; I may have to try that myself. I have to confess, though, that I actually enjoy chard with some of the younger chopped stalks added in. As you say, tastes differ... what a boring world it would be if that were not the case.