The other thing to consider is we are "hobbyists" trying to provide the ideal, long-term environment for the fish and their best interests...not a LFS or it's employees trying to sell us on something or displaying multiple large specimens in an under-sized tank trying to get us to believe that it "works".
Truth is, the LFS put all kinds of big fish into little tanks, but they will not be there for long because they sell them. We, on the other hand, have to look past that mentality and realize that "sure, we can put these fish in our tanks, but eventually there will be a price to pay".