Brittle stars are fine, they can find food in the rocks and stuff. Sifting stars need the sand to be dirty enough or they'll starve.
That's the issue with cleaners. They are a janitor and a pet. So you wind up balancing enough food for them with not so much food that the water gets dirty and grows algae. All the critters in the sand and rocks poop too. So you have different schools of thought, I would describe it as either (1) removing the poop before it can become fertilizer; (2) hiring a janitorial staff to eat the poop, and each other's poop until there's nothing left to become fertilizer; (3) letting it become fertilizer and running gfo or algae in the sump to compete with the algae for the nutrition.
Most people run some combination of the three to achieve nutrient (phosphate and nitrate) levels that keep their coral happy, since coral don't grow well when there's fertilizer in the water, but algae does. The combo you choose is just a matter of which methods appeal to you. It's not like there is one trick that eliminates tank maintenance, you're still going to be pruning algae, dumping a skimmer, replacing gfo, vacuuming sand, changing filter socks or rinsing floss, replacing a dsb in a few years, etc.