Maybe they do for some people, but not in my experience. I get the impression (perhaps incorrectly) that the people who report troubles just find one gear and stick with it for miles and miles, and then are surprised it's stuck there by icy build-up.
I run full fenders with mudflaps, which keeps a lot of crap out of the drivetrain to begin with. I also run close-ratio cassettes and shift frequently, due to the stop-and-go nature of my route. That keeps the cables and RD freed-up and minimizes build-up on the cassette.
But also remember that my commutes are short (about 5 miles, 8 km) and I park indoors at both ends. Maybe that helps too, I dunno.
Basically the same here. I have never had a derailer freeze up on me. My commute is 5 miles. I also park indoors. But, I don't shift much. West side of Cleveland is really flat, I typically only use 2 gears.
Going car free is pretty easy for me. Everything is somewhat close. If I need a motor vehicle, I just rent one. It's cheaper to rent a car for a day or two once a year than it is to own one, even if it just sits all year long.