I used to change my carbon but really I don't think it's worth the hassle. I did a test on my two 10 gallons one I changed the carbon and the other I didn't change it. When doing proper water changes I couldn't tell the difference in water clarity or quality. I still keep some carbon and a whisper internal filter around for if I ever need to medicate a tank. Also there is much debate on how long it actually is effective. One good thing about having some in your filter is it does provide extra surface area for your beneficial bacteria to colonize if you just leave it. I personally use sponge filters in my tanks and my water stays just as clear as when I had the internal "3 stage" filters. I'm not saying they don't work, but with proper maintenance I don't think you are going to tell a difference between a sponge filter by itself and a "3 stage" (mechanical, chemical, and biological).
The article does make some good points. My only problem with it is lack of sources. It's okay if he is just presenting this as opinion, but a few sources at the end wouldn't hurt. Back to the point, carbon isn't all bad, and I do keep carbon filter cartridges for my tanks hanging around. Mostly in the event that I need to use medications. My problem with carbon is that it give new aquarists the illusion that all they need to do to "clean" a tank is to change the filter cartridge. Yes carbon can make the water look clear, but it doesn't provide clean water like regular water changes will.
Activated carbon binds the medication to it and takes it out of the water. It's really just to clean up any residual medicine as most meds instruct you to stop water changes when dosing. You really should do a water change after a round of medication. The carbon just helps make sure it gets cleared out.
Carbon removes medications from tanks. Both dyes like methlyene blue and victoria green and antibiotics like acriflavine (in case anyone is wondering about the specific examples I have a box of API fungus cure next to me). Carbon can also be used to remove toxins from humans, too. Colobus monkeys eat charcoal to help remove cyanide from their system as their leafy diet causes them to consume a lot of cyanide. Last time I used carbon was to prevent any antibiotics from floating around in the water when I was feeding my goldfish medicated food. Didn't want to hurt my biological filter.
I don't think there is anything wrong with using activated carbon, but I don't - I don't need it for its function in removing medications etc, so I replace it with more porous media for better biological filtration.
I have set it and forget it filter cartridges. XD I stick them in... and leave them. I swish them around once in a while to get the gunk off, haha. They came with carbon in them, but I never replace it or the cartridge. I have a lot of tannins in my water, but it doesn't bother me!