What LFS do, and what 'should' be done aren't the same thing.
Remember that the LFS tanks are for 'temporary' stocking while they look to sell them. Meanwhile, your home tank would be 'permanent'.
For example, you can temporarily house a fish that will grow very large in a small tank, but long-term that leads to stunting and deformation. Or, you can temporarily ride an elevator with a bunch of folks, but wouldn't want to live in there.