But in reality, the ideal system is probably a combination of built-in redundancy / spares for parts that can work that way; and then robots for the kinds of things that are too complicated to have a built-in failover.
Robots don't need air, food, or sanitary facilities.
Launching to space is severely constrained by the mass you can bring up. You can send up multiple robots compared to the mass needed for all the food, life support ect, for a single person.