Discus are not hard to keep, but they are very sensitive to dissolved organics and nitrate in the water and will very quickly stunt out at a small size if you aren't careful. People always balk at water changes with discus, but there's a reason so many discus hobbyists recommend them -- they work. We don't do them because it's fun or because we want to, but because it's been proven over years of discus keeping that the key to large, healthy fish is very clean water.
Aside from nitrates, there are other types of dissolved organics in the water. Discus eat so much as juveniles (and in turn put off so much waste) that it's hard for aquarium plants to keep up. Discus keepers have tried for years to find ways to absorb all the DOCs and nitrates in tank water via natural remedies such as plants, but most don't rid the tank of it fast enough to be very effective. Remember, discus are shoaling fish and in order for the pecking order to work, it's always best to have at least 6 fish (sometimes you can get away with 4). Considering that most people start out with a 55 or 75 gallon tank and 6 cichlids, that's a high bioload.
My suggestion to people is always to start with larger discus if you're doing the planted/decorated tank route. Small fish need the extra food and water changes to really put on growth and develop properly. It's just easier in the long run to do water changes and wipe down the glass on a bare-bottom tank. Once adults are past the crucial growth and development period, usually after 12 - 18 months, you can cut back on food and water changes. These are the best fish for a display tank.
A lot of people get by with one weekly water change and one or two feedings a day with adult discus. This is more in line with other South American cichlids and it shouldn't be any different than those of us keeping geos, severums, oscars, etc. The difference is with the young fish, and not everyone wants (or can afford) daily water changes.
Simply put, everyone's maintenance schedule should be different because everyone has a different tank size, number of fish, filtration, source water, feeding routine, so on and so forth. If you keep 6 large discus in a 125 gallon tank without other large tankmates and you only feed them a couple times a day, you could do one large (50%) water change a week and be fine. Just remember to keep your filters clean and the nitrates low. If you start packing more discus into the tank or upping your feeding, or if you start with small fish, all that changes again.