I'm sorry, there is no disagreeing. You may enjoy snowmobiles and sled-accessed backcountry skiing, but that doesn't make me wrong.
Let's try some points, I'll work a few angles with a simple yes/no.
Do recreational snowmobilers help the ski industry or ski resort economies? No, not measurably. While they may serve to access terrain for promotional media, they do not directly bring money to ski equipment manufacturers or most ski areas.
Are snowmobiles environmentally detrimental? Yes. Well they certainly aren't beneficial. The degree to which they do harm can be argued, but there is no argument for positive influence.
Are snowmobiles safe? No. Averaging number of sled-related deaths and accidents by the number of them on the hill doesn't apply here, the fact is the death toll has surged. Increased backcountry use doesn't make it any better or safer, it just increases the human and environmental toll.
Do sleds progress skiing? Arguable. Yes they access better, less utilized terrain more easily, but plenty of ski film segments, even movies have been shot inbounds or near inbounds. While it's not a big name example to most, nor is it progressive in the newschool sense, but many of the lines from Parental Advisory are visible from Whistler/Blackcomb chairlifts.
Here's where you win. Are sleds fun and easy ways to access the backcountry? Yes, of course.
But that wasn't my point. My point was that a sled benefits only its rider, whereas the effects of people sledding affect many more people. You can say, well, it's a small number, not nearly as bad as cars, cats, resorts, helis... etc, but as an increasing addition to the sport, the benefits don't even touch the detriments. It benefits you as a rider alone, it is therefore a selfish act. Yes, skiing itself is too... but it's a further addition.