Rules of thumb like get a filter whose flow is 10x the volume of the tank is as bad as one inch of fish per gallon of water rule, IMO.
One thing I wanted to mention... People convolute filtration with flow.. they are two different things. I usually ignore people who blindly say you need more filtration when they really mean to say you need more flow. I like your write up, just want to hammer home the point that filtration contributes to the amount of flow in the tank, and adding gentle circulation pumps is usually a good idea in general. The idea of people getting one super powerful canister filter , for example, to achieve the correct flow when they could have a reasonable sized filter with multiple powerheads cracks me up. I treat mechanical and biological filtration separately in my 55 gallon planted tank. Rules of thumb like get a filter whose flow is 10x the volume of the tank is as bad as one inch of fish per gallon of water rule, IMO.