This is very misleading. Most of the discomfort would be from the hard table against the back of your hand, and this would be because of local pressure on specific points.
Good point, but it feels about as uncomfortable if you use a padding over the table that eliminates the stress concentrations at your bones and knuckles. Especially if you double the dumbbell weight and recognize that it's only a pressure increase of 10%.
I don't agree with this.
Your thought experiment with the dumbbell is an incorrect way of thinking about ambient pressure. Ambient pressure pushes against an object from every direction. It does not work to deform or break, only compress from all sides.
Picture this: You have a hand-sized water balloon on a table. You place the two dumbbells on it; it breaks. You have another water balloon. You take this one, tie it to a dumbbell, and drop it into deep water. Do you expect it to break when descends to 3 feet (i.e. 10% increase in pressure)?
I would not expect...
There's a lot of background mess in our mental pictures of the world. We try and be accurate on important issues, but a whole lot of the less important stuff we pick up from the media, the movies, and random impressions. And once these impressions are in our mental pictures, they just don't go away - until we find a fact that causes us to say "huh", and reassess.
Here are three facts that have caused that "huh" in me, recently, and completely rearranged minor parts of my mental map. I'm sharing them here, because that experience is a valuable one.