Why do dinnerware sets come with so many mugs?

Does anyone really use them? I only know people who use mugs for coffee or hot tea and even they rarely use the mugs that match their dishes.

I do realize there are people who use them often, but are they a large part of the market? Wouldn’t coordinating tumblers be just as useful, if not more?

Just something I have been contemplating while looking for a set of dishes. Put those mugs in an optional add-on purchase and save me some money!~