Depends what you're talking about, in conquest mode it's pretty even but i do see indeed a lot of bad players in the allied side who lose their ground when they shouldn't, then who litteraly throw away their vehicles in front of at guns and panzers like candy.
You're exagerating a bit. 10 to 15 KT ? You kidding ? When ? In the last 5 minutes ? Means you've 5 or more 5 decks to have KT and they all are going for it. It is not that common. 10vs10 brings a a lot infantry decks and all the german armor players don't wait their KT, they bring their tiger and Befehl Panther to push their luck.
I play often lehr and i almost never bring 2 or 3 KT or it is the very end of the game and i'm against a sitting player or one IA since 20 minutes.
It is not KT which make you lose or win 10vs10, as you say the game is usually decided at the very end. It is mostly sitting ducks who makes you loose. In destruction mode, noone is pushing as noone wanna loose units and you canno't let an armor german player build his strenght. You've to harass him. That is why destruction mode is unbalanced for allied players. When you do harass players you loose unit and when you do not, you loose units (as the line doesn't matter a lehr may fall back and regroup).
But in conquest, it's all about delay, you don't have to kill german panzers, you have to delay their advance time enough after you've made a lot of points in phase A and B. A german player must clear forest and tree lines before advancing his panzers or he risks to fall on ambushed 17 pounder. Good players will wait the right range for their AT guns to fire. They'll throw infantry hidden in treelines, they'll smoke, panick tanks with arty.
I assure you i've played 10vs10 when allied players do these things and win the game, they have heavy losses but who cares, they fight for terrain. Usually they don't, they play conquest like it is destruction (and do not try to push) or destruction like it is conquest (and throw their unit away)...