It all depends on how you 'look' at the numbers but they do have to have diminishing returns because they add a % instead of a flat number. Ok that might go over some heads and I probably said it wrong so I'm just going to pull imaginary numbers outta my bum to show example.

Attacker does 1,000 damage, each tac console adds 100 damage.

Defender has 10,000 hull, each armor console adds 20 resist.

So with 0 consoles on both sides it takes 10 shots to kill the defender.

*note I do not know if this is the true resist formula*

So lets give them each 2 consoles.

Attacker does 1,200 damage

Defender has 10,000 hull with 40 resist or 28%

Attacker only deals 860 damage per hit takes 12 hits to kill target

Now lets go nuts, 6! consoles muhahaha

Attacker does 1,600 damage

Defender has 10,000 hull with 120 resist or 54%

Attacker only deals 736 damage per hit takes 14 hits to kill target

Now how a normal game design would handle that would be to add things that reduce a target's resistance by a percent, so the more resistance they have the more they loose and it is a real question of if you should focus on the penetration or flat bonus damage. Or they would have limited methods to increase your resistance in the game heavily and allowed you to gain bonus hit points/hull instead.

But no, we get diminishing returns and a system that gets really skewed when the numbers start getting too big.