I fear such comments are only the typical reaction of the modern Westerner, as we have come to view the two-child family as the norm. I'm not saying 19 children has ever been the usual number, but plenty of people would find 19 to be much more reasonable than 2 or 3.
I think everyone you talk to has some number they can't imagine. At this point, my parents get gasps from some people when they find out that they raised 4 children!
I was the oldest of of the four, and I was expected to pull my weight around the house in the form of chores and helping out with my younger siblings. It only made sense that I should he out with things like meals and sibling's homework. I think this dynamic had the effect of building a stronger family, as everyone (kids included) had a part in the running of the household, rather than the dynamic I see today where many parents are essentially servants for their children. Hell, I can't remember the last time I saw a teenager mowing a lawn.
Another interesting thing about the US in the past few years is how the family has gotten considerably smaller while the size of the typical house has grown. Now you will see a dynamic where family members all retreat to their respective rooms in the evening to watch enjoy their own TVs, Computers etc. There is less and less sharing of spaces and devices. Kids sharing rooms (as I did) is now looked on as something odd, or something only poor families do.
The Duggars certainly have more children than my wife and I would attempt, but they aren't placing a burden on the welfare system, unlike many families with far fewer children. It doesn't sound like their kids are getting into any trouble either.