That’s a bit naive and very unrealistic. Constitutionally, Congress has the responsibility and the power to declare war. They also have the sworn duty to perform all of the other Legislative functions and, therefore, would be leaving the Government unable to function, during a war, no less, if they went off to fight. Besides, most of them are too old or physically incapable of serving, never mind that an army of 535 would be pretty much the same as none at all.