I ride single speed and I can tell you with certainty that there is still shed loads of maintenance.
There is more with a geared bike granted. Cassette, derailleur etc but you still spend a considerable amount of time maintaining the bike especially for xc duties.
Most people dont ride single speed because it reduces maintenance. That is only a small factor. They ride single speed because its without a doubt the purest and funnest form to ride.
Hammering the trail and putting the power down whilst out of the saddle is incredibly fun. Silence etc is just a biproduct. The real reason to go single speed is fun. In abudance.
Sorry, my mistake … I bow to your superior knowledge, please accept my apologies.