Yeah I don't think anyone is under the impression that any smart phone is not powerful enough to do this, but have you actually tried development on a phone? Even with a keyboard this is masochistic.
But many seem to think that smartphone implies being limited to mobile apps to do work which fortunately on Android isn't the case. Tried to see if it's possible but no, I haven't used it to build something substantial. I didn't mind that much the small display as the lack of keyboard. A phone with slide out keyboard will probably be a fine choice for this usage.