SpeedFan can report the speeds of each fan and it can even change their speed based on current temperatures. This lowers noise and improves computer experience. SpeedFan can access the voltages reported by the hardware. This can help to identify odd issues with computers resetting under stress, for example.
So while securables created by the database owner actually are owned by dbo, this is still the user that created them. Also, most objects are probably not created by the database owner itself, so this still does not explain why most securables end up with dbo as owner.
Fixed-database roles are defined at the database level and exist in each database. Members of the db_owner database role can manage fixed-database role membership. There are also some special-purpose database roles in the msdb database. You can add any database account and other SQL Server roles into database-level roles. Each member of a fixed-database role can add other users to that same role.