Come on, I don't think anyone is saying we should drag unwilling people kicking and screaming to the other side of the DM's screen and start throwing their favorite dice in the fire until they start running a session. Going outside one's comfort zone is a good thing because it provides them with an opportunity to grow. Sitting behind the DM's screen once in a while is good for the following reasons:
- It's a good opportunity to stretch your role playing muscles by playing several different NPCs.
- It's a good opportunity to to gain a better understanding of the rules.
- It's a good opportunity to plan out an adventure or at least follow an outline for a prewritten adventure.
- It's a good opportunity to learn how to adapt when PCs dash their well laid plans or do something the writers of the adventure didn't think of.
- It's a good opportunity to experience the game in a new way.
- It's a good opportunity for the regular DM to be a player.
- It's a good opportunity to better understand and appreciate the DM for what he does.
When we say you should try DMing we mean that in the same way when people say you should get out more, you should eat a little bit of everything, or you should call your mother more often (seriously, she loves you and wants to hear from you).