The reason is very simple. It slows the fermentation. If for example you made a pizza dough and left it out for 3 days at room temp,
the yeast in the dough would be expired, meaning there would be no power left it in, or very little.
By placing the dough in the fridge, this slow the fermentation, and you can then keep doughs much longer. This is totally natural
and is done all the time in pizzeria places around my part of town.
As for the example of a dough under 24 hours, I guess one would have to know how much under 24 hours you are talking about.
If you are closing in on 24 hours, you will get a better dough if it is refridgerated, the yeast will get sleepy, and slows down.
If you are talking about 4 or 5 hours then I agree with you.
I am not an expert pizza maker but having worked with pastry and bread for quite some time, you let yeast do its thing and you have to
keep an eye on the hours it works and is out at room temp, miss your door way and the yeast starts to die out, and then breads start falling.
For example I don't understand why using the refrigerator for fermentation below 24 hours. This does not make sense to me. The only reasons that would justify this, would be a very wet dough (110% flour to 100% water) like the one they make in Rome for pizza al taglio or pizza romana.