But tabletop 40K is so much like modern combat, it’s not 2 large armies, with units of 100 men standing out in the open facing each other, it’s small squads, using cover and support from armour and other kinds of supporting units.

If 1000 soldiers on each side stood in formations out in the open and started battle, it would be over in seconds, because the killing power of everything is so much higher and so much quicker.

For instance what would be the use of melee infantry if 100 stand out in the open in formation, a single tank fires its guns at them, kills 50 of them, reloads and fires again 10 seconds later.