Big tech has this uni-modal aporoach to users: they find what maximizes a metric, and works for 75% of the users, but roll it out to 100%. Dealing with the remaining 25% would have low ROI.
Large people are out of luck.
But your point still holds, it is just that if you include children, small sizes don't follow a normal distribution, large sizes do.
You sound like you have not dealt with humans at the scale of the number of smart phone users. I've never dealt with the numbers of something like an iPhone, but over the course of my career have had multiple SKUs totaling over 1 million units. No matter what, there are always "people on the internet" that are dissatisfied enough to go online to voice their opinions. That's the only 100% is that there will always be someone unhappy for whatever reason(s).