I wont speak for Mo, but to me, for the most part, "overstocked" means population/species rates different than they would be in the wild (and yes, I know its not the wild and theyre in a glass box etc etc blah blah blah...but aesthetically speaking.)
Those fish wouldnt live that close to each other in the wild because they simply wouldnt tolerate each other (or find each other if geographically different). When you MAKE them do so, other adverse affects take over with their growth rates, eating habits, reproduction habits etc etc etc.
That many fish in an 8ft tank (which really isnt that big compared to how theyd live in nature) wont thrive. They may get 10+ inches, may eat like you (we) expect them to, but they wont act natural...and it is about "trying to cram as many fish as possible into the tank" if theres more than 1 large pair with some smaller pairs of less aggressive fish around, like there would be in nature.
How may 300g tanks do you see with 1 pair? or 265g with 1 pair? or 125g with 1 pair? Hardly any because thats a "waste" of tank space by MFK standards. Not speaking specifically of you or anyone reading this, but these fish are mostly possessions, bling, bragging rights etc on MFK, not really what one would describe as "pets".
Not many people on here (aside from ones with mental disorders) would cram as many dogs in a kennel as we do fish in an aquarium, especially not breeding pairs or aggressive males/ females and expect any rate of success of compatibility, would they? And if someone answers yes to that, to me, their opinions dont matter because they arent too humane or bright to begin with. With fish we just dont suffer the instant mortality rate you would with keeping other animals in such confined quarters.
"Overcrowded" , like most everything else on MFK, is subjective at best. What works for some doesnt for others & vice versa.