The faction can also deploy some of the most powerful tanks in the game, the fearsome King Tiger and mighty Jagdtiger.
They are "most powerful tanks in the game" in name only. It's purely thematic, and I never build them ever. King tiger is so ridiculously slow and the turret traverse so slow that it might as well be a glorified tank destroyer. Jagtiger can sit in one place on the map behind buildings or trees, protected by a blob of ATG, and that's all. Sturmtiger is a joke, etc. All of this stuff came out of the box pre-nerfed and useless.
With the amount of unique things the OKW brought, it became difficult to balance this faction in relation to other factions.
None of this stuff in-game is difficult to balance. The balance team simply doesn't know what it is doing, doesn't care, is lazy, or doesn't have the resources/time to sit down and balance the game. I'm not flaming relic just for the sake of flaming them, I am simply stating the obvious.
Even before OKW/USA hit the field, how good of a job do you think the balance team was doing, and how difficult was the game to balance? I'd say the answers were "crap job" and "fairly easy."
The list of things they got wrong, didn't address, still haven't addressed, etc. is a pretty long one, and again I'm just stating the obvious. What's so hard about balancing the su76? What about the wehr flame halftrack? The unit is an absurd, pathetic joke and anyone with half a brain knows it.
There were many unintended consequences such as the Kubelwagen being viciously strong
Kubel was 100% joke when the game came out and needed buffs. It got buffed but allies cried so it got re-nerfed. Now it is useless again, and OKW is again left without any non-doctrinal HMG.
All OKW support weapons are either non-existent (sniper, flamethrower, mortar, HMG), suck (ISG), are too expensive for what they provide (infrared ht), or are too inefficient to be used as any reliable counter (stuka).
Having said all of that, No matter which side of the issue anyone is on (allies/axis), I don't think any of these things are hard to balance. Kubel could have been adjusted and swapped with MG34 (i.e. made doctrinal) - in fact I suggested this very thing on relic forums when game shipped; ISG can be buffed and have price reduced; etc. etc. etc.
100 percent muni income affecting team games
Again, an easy, no-brainer to fix. And again, I suggested that fix on relic forums: simply adjust downwards the amount of income OKW receives from wehr caches. But what did relic do? Adjust the entire munitions income downward for all game modes.
In closing, the OKW's mechanics make it extreme hard to balance the game....
Do the players believe the OKW are a main cause for many of the game's balance issues?
OKW mechanics in no way make it hard to balance the game, and OKW is in no way the main cause for many of the game's balance issues. The problem is that there is no balance team.