Hello; When in a hole stop digging. I get that shops have a lot of stock and pretty much have to keep fish in too crowded conditions. I figure the hope is they move the stock often enough that it is not long term. I also get that WC and large sumps help in a commercial setting so yes it can be gotten by with.
The folks on this forum are the customers who, I am guessing here, want to keep a fish long term. The "you can do something and be able to get away with it" hole has clear flaws. When I was young and uninformed I overstocked, overfed and did not do WC. I have learned better and keep very light stocking, feed sparingly and do WC. While my current practice is so much better for the fish I keep there is a downside.
That downside is that I simply cannot keep the wider variety of and number of fish. My tanks have minimal numbers of fish and not much variety such as I had in the past. I get most of us want, as I did in the past, to have lots of different and interesting fish. Many want the bigger species as well. So the concept of being able to get away with it is appealing. Has more to do with the wants and wishes of the fish keeper than with best care practice. I'll bet there are many who keep wishing for some trick or practice they can find so they can squeeze a few more fish in .
I may be wrong about this but have gotten the impression some feel having massive power filtration is just such a trick. I get this impression from reading threads.