A skimmer isn't required for ANY tank...but will help reduce your maintenance load if present.
Anyone experiencing water that is "too clean" to the detriment of their corals has something else going on besides protein skimming...probably using chemical filter media and/or overfeeding, but there are lots of things possible.
If I wanted to set up a softy tank and didn't have a skimmer for it already....I'd definitely set up the tank and stock it without a skimmer just to see how it goes. I'd keep the fish list short so the bio-load is on the low side. I'd plan on weekly water changes...using them as a chance to remove (at least stir up) any detritus in the system.