How come it becomes a debate on whether its a computer or not?

Come on, it so simple.

Just take out anything and tell people it's a computer. If you don't receive laugher as response then it's a computer.

(take out iPhone) "It's a computer"
"MUHAHAHAHA what an idiot are you?"
(take out N900)"It's a computer"
".........................oh btw how's your day"

See? No debate needed.