Because of people that want to have it both ways.
Its ok that 50 munitions without a mouse click insta destroy a 270 Manpower + 70 fuel vehicle but it was NOT ok that 90 munitions + 1 click (old demos) could insta wipe a 200 - 360 manpower unit.
Try to argue against this logic, I tried and I failed
You can always sweep for your one light vehicle. You can't always sweep for your 8 infantry squads.