>>1718901I've researched this subject myself and found that a lot of people swear by them. In winter riding the simpler the bike, the better. All those exposed drivetrain components really take a beating from the road salt, sand and debris.
However it goes without saying that you'd probably need a dedicated gearing for winter riding on a fixie, and fenders and winter tires. So either a dedicated bike or swapping the rear cog and front chainring each time.
A singlespeed freewheel with a rear coaster brake would also be good in winter.
https://www.sheldonbrown.com/winter.html 