Kuiu's lightest softshell top weighs a pound, but won't loft like fleece. The same weight in fleece, or a bit less, won't block wind well but will absolutely hold moisture out against your shell in the wet, keeping important stuff inside dry. A softshell might do the same thing under a shell, but it will wet out and won't dry nearly as fast as fleece.
Wind strong enough to render ineffective exped-wt baselayer or fleece midlayer (when moving) is easily blocked by a puff vest, puff jacket or shell, and in that sort of wind, quiet clothes don't matter as much.
About the only place I can see for a softshell top is below 25F, crapping down snow, and you want to move quietly or otherwise hear more around you than the rustling of your shell. Take any one of those three conditions away, and you can do better, lighter, with other things, with a system that will handle the conditions at the possible expense of some rustle or swish.
Softshell tops truly have no place in the wet - their highest and best use is as pants, but only because whipcords are cut for people who don't squat. If someone made a simple whipcord wool pant that fit like Carhartt B159s and didn't have a bunch of really bulky belt loops and crap to bunch up under my waistbelt (like Sitka...), I'd own them. That there would be the pant of excellence.
