Well yeah, of course if they have all perfect items and are maxed out and you have none, you're not going to get there regardless. Like you said, nothing's going to overcome that gap.
My point was that, if the difference is only 1 mythical plate vs 0, or maybe even 2 vs zero, there's still a decent chance to win depending on how the turns play out.
I've had tons of games where, even though I'm playing vs a mech with 200-300 more HP, the turns play out so that I'm almost dead but it's my turn and he has 400-600 HP left. That's a win.
I'll admit than 2 plates to 0 is pretty hard to overcome, and obviously impossible if you have something like 3 mythical plates and a +39 resist all plate. But that's rarely the case. If I had an an all-mythical mech minus a plate or two, I'd could still be in the top 20.