Historical context: The United States was a colony of the crown. The tyrannical government they feared at the time was coming from Western Europe to claim colonial control of the land. The authors of the Second Amendment had no conception of semi-automatic or automatic weapons, weapons of mass destruction, a bicameral legislative system as a part of three part interconnected system with checks and balances, a wavering state-power system, nor an anarchical system of world governance. Mass-shootings were not in existence at the time, nor were militaries completely separated from the civilian population. If you're going to ignore the historicity behind the amendment, don't try to argue using it's creation.
And an argument of legally futility is incredibly stupid. The government seizes illegal weapons constantly. Should we abolish laws against hardcore drug use or sexual abuse as well because the law cannot possibly prosecute all cases? Of course not. Gun control should be in place regardless.
If a tyrannical government forms, there isn't even a snowball's chance in hell a bunch of weekend warriors and petty gun owners could possibly stop it with their poorly-modified AK-47s and cargo pants.