My opinion might differ just a tiny bit. But then again, I usually have different goals as well.
I wouldn't use a sponge filter only for any of my reef based systems but I AM going to use a significant amount of sponge material for my 715 gallon FOWLR shark/ray tank filtration. Keeping sting rays means minimizing the amount of live rock that I can place along the bottom of the tank which limits the total LR volume and that means I can not depend on the LR alone to complete the Ammonia -> Nitrite -> Nitrate > Water Change cycle without some assistance.
I'm building an inexpensive bio tower with multiple layers. The first will be disposable filter floss to collect large to moderately sized particles. Next will be a felt layer to trap small particles followed by one or more layers of 20 ppi foam. Keeping detritus out of the foam will be very important to prevent unwanted decay byproducts flowing back into the tank. The foam is going to always be wet but suspended above the water line promoting aerobic (O2 loving) bacteria that perform the Ammonia to Nitrite conversion.
I will then have a lower flow remote refugium fed water after the biotower with anaerobic zones to encourage bacteria that converts the Nitrite to Nitrate.
Lastly I will have live chaetomorpha macro algae in the 'fuge along with a bio pellet reactor and dedicated skimmer to help absorb Nitrate and Phosphates from the water. This should help cut down on the frequency and volume of bi monthly water changes needed to keep the chemistry clean enough for the fish.
Sorry if this is a more technical explanation than you wanted. I don't view anything as a "factory" except for the shark. He is a poop factory and hence the need for everything above.
Feel free to love your sponge filter. Used in the correct way and context, they are nifty! IMHO
