in my view it is very important to keep your chain clean and well lubricated.
It doesn't, make very much difference.
A wipe with a rag and application of any sort of lube. I never touch the cassette or rings.
My cassettes and rings last 20,000km's and chains between 5 and 8000km's.
Yours won't last any longer, nor will you ride any faster.
A shiny clean bike looks nice but I couldn't be bothered.
Bearings are sealed but not very well compared to say automotive bearings.
Constant application of degreaser and water will very likely find it's way into the wheel and free hub bearings, diluting and emulsifying the grease and shortening their life.