It's not stupid nor is your analogy apt.
All it takes is one user not using SSL or not verifying certs for your chats to be vulnerable to eavesdropping.
As well as all it takes is one gmail user for your email conversation to be vulnerable to eavesdropping.
Is this a reason to say SSL between your email client and server is useless?
Just because the NSA can also connect to the server, join the same channels you're in, and see your conversations does not mean SSL is "useless".
It's like saying that locking your car doors "is useless" because someone can just smash the window in.