I’ve just changed the chain, sprocket and chainring on my hub geared bike after 4 years of all year round off road commuting. In that time I’ve never cleaned the chain beyond a quick wipe over with a rag and the application of whatever oil is lying around. The cost of the parts was £70 and in another 4 years the chainring will be reversed so it will be cheaper. No conditions I’ve encountered so far have stopped the drive train working.
The only advantage I can see with these alternatives is that for town bikes they are cleaner and belt drives are both cleaner and significantly lighter.