Really? So is a filter a bandaid, too?
Negative. Good filtration is a necessity. However, that pesky H2O people keep adding to their tanks.... Let's just say that it has been found in the tanks of all people with algae outbreaks.
Sure, you may look to use it if you are already having problems, but why not use the best filter media possible to help avoid problems in the first place?
Because it can cover up emerging problems that can be addressed with a little more work. There are a lot of people with beautiful planted tanks that are not running Phosguard, Carbon, Purigen, or anything else aside from basic filtration and carefully balanced nutrient schedules. Please understand, I'm not attacking your maintenance habits or methodology. However, I do believe it's best to run as close to a natural system as possible (in an unnatural environment..) and adjust as needed.
On my reef tank I run a protein skimmer but I also run ROX Carbon and GFO. Water quality with saltwater is extremely important so I'm used to using preventative measures, with water changes being the first line of defense.
I don't know about Marine. I have no experience with them. I do know that planted freshwater tanks are unique in a lot of ways in that the plants and livestock form a mutually beneficial symbiotic relationship. A relationship that mitigates the need for a lot of the things often run in a non-planted tank.
Just my $0.02, and opinions are like buttholes. Everyone has one, and they all stink.