I think there are good and bad players. I think, to a smaller degree, there are good and bad builders. Mostly, I agree that items are the truest difference maker. Specifically it is claw, plat plates and protectors that change the game. Look through the ranks for whatever proof is required.
Weapons can impact things, but the best weapons and builds don’t overcome the high HP and resist items. I have 2 well built mechs that lack claw and/or plats. It doesn’t matter how good my weapons are or how well i play, when my combined total of HP is 1800 less than the combined total of my opponent, it is no longer 2v2, it is 2v3.