OK....but most people don't want to buy more fish than their tank/biofilter can handle as adults because they don't want to have to get a new tank or get rid of a fish if the fish grow too big one day. Not to mention if you wait until your biofilter literally can't handle anymore you have absolutely no safety margin for an accidental overfeeding day or something. It's riskier than most prefer. So most would rather use some way to predict what the tank can handle before you actually hit the cap of what the biofilter can handle.
No stocking advice is perfect and I certainly didn't imply I had the right answer. I just suggested they make sure the existing schools are happy before they consider adding a new school. And actually the only reason I mentioned that at all is because I recently had the same 'revelation' in my own tank, going from several small schools to a couple bigger ones produced much more fun behavior for me to watch because the fish felt secure enough to spend more time out of the plants@
I do agree with you though, jarrod0987, that sometimes people get a little overstrict with their 'rules' about what a tank can hold. They're intentions are good though!