Yes.
Actually, what I want to say is: having continuous armor/piercing mechanics on top of continuous hardness/hard attack mechanics is worst solution. You would end with two different systems that (conceptually) do the same, but each of them in different way, with only most math-inclined players understanding difference. Compare it to current system, where interaction is very straight forward ('more armor than enemy piercing good, less armor than enemy piercing bad, there is also hardness I guess').
As pro.gamer.69 said, they are different concepts. Countries developed weapons to kill enemy soldiers using bullets and explosives. Since human don't vary that much in size (unlike, for example, dogs), personal weapons like rifle and (light) machine gun bullets generally don't exceed 8mm in diameter, and heavy machine guns that can penetrate covers and non-armored vehicles generally don't exceed 13mm, as anything more than those would cause too much recoil for the average soldier and reduce the amount of ammo they can carry.
Then tanks were invented to be protected against such weapons as well as shrapnel from explosions. Despite their appearance, the standard caliber of infantry weapons did not increase accordingly. Rather, specialized weapons like anti tank guns and rocket launchers were invented instead. The reason was that the physical characteristics of soldiers hadn't changed, and infantry were still expected to fight other infantry most of the time, and here's where the hardness and soft/hard attack distinction came from: hardness is the % of a unit that's immune to anti-personnel weapons, soft attack is infantry weapon damage, and hard attack is damage from larger calibers/anti-tank weapons.
(Side note: I've seen many arguments on how it doesn't make sense for AT weapons to be ineffective against unarmored soldiers so here's the reason: while it's true that a 37mm AT gun will obliterate anyone it hits, a bolt-action rifle can reload and target the next enemy faster, and there are way more rifles in an infantry battalion than guns in an AT gun battalion. That's why AT weapons have relatively low soft attack.)
On the other hand, penetration and armor work in a totally different way: hardness determines what kind of damage the unit is susceptible to, armor/penetration determines how much damage it actually takes. The values are weighted average across the whole division, so it's not just literal penetration depth and armor thickness. Armor and penetration stats vary according to the % of the division they make up presumably to simulate the occasions where tanks have to present their less protected sides and rear and the numbers of enemy tanks/AT guns present to exploit their weaknesses, so fewer tanks with more infantry in between makes the protection less effective. But this is where the binary penetration doesn't make sense: the 50% damage reduction perhaps represents the tactic of using two weaker tanks to outflank an enemy tanks whose front armor is too thick in order for one of them to attack the thinner side/rear armor, but with the weighted average armor/penetration calculation, this doesn't make sense: While having 20 instead of 24 AT guns in your division does make it more susceptible to the same enemy tanks, it doesn't make sense that you should suddenly take twice as much damage. Similarly, adding one more infantry battalion to an armored division would make the tanks provide less effective cover, but it should be gradual instead of a sudden cutoff.
