In my experience gestalt throws what we know about casters vs martial under the bus. My group has found casters to be underpowered in gestalt games. This is because gestalting a caster will have very little effect on them if they focus on being a caster, while they certainly end up with more casting options, they are still limited to the same spells per round as in non-gestalt games, and those spells are no more powerful from gestalting. Which leads to my next point;
I've said that I find Gestalt casters to be underwhelming. And you would know this if you read my post.
With gestalts your action economy does change. Instead you have more options of things you want to do. Sure being about to cast a spell and swing a sword is good, but you only get to do one per round. Instead your better off focusing. This is that makes rouge/barbarian so good, neither a abilities steal from action economy(and as an aside, if a rouge isn't getting sneak every round, they are doing it wrong). On top of that what they do have stacks, both in and out of combat. The both bring different benefits to the same goal. That is the real trick of it, not trying to do too much with one character, which brings us to point three;
You're just wrong because you don't actually gain any more capability to do a specialized task with a Gestalt build, but by focusing so narrowly you're paying a huge opportunity cost since you could have instead broadened your character's options such that you were never told "sorry, you can't do this thing no matter how hard you can swing a sword".
So if you hang out on this sub, your familiar with feat taxes, they are the bane of a gestalt's existence. You first need all the feats you normally want for a build, then you want all the feats that make your other character nice. This is hard and makes certain combinations terrible, and others have an edge. This is also the benefit of fighter/anything. It is important to remember that the whole idea behind fighters is that all those feats make up for their lack of other special abilities. So with gestalt, having those extra feats means more choice and that is key. It is not the only way to do but it is certainly the best way (I would like to mention here that one of the most OP gestalts I have ever played with was an inquisitor/fighter. This was because they had an AC, pre-buffs, 15 higher the the rest of the party, and was no slouch on the battle field. In there defense, we told them we really needed a tank, and they were just trying to be a good match for the party.)
Not having feats is exactly the reason you should pick up complimentary class features rather than narrow your focus with classes that step all over each other's toes.
You're pulling nonsensical, illogical arguments out of your ass and fooling yourself into thinking that stating something confidently makes you right. Sorry, but in this case, you're just wrong and trying to start a fight. Fuck the fuck off.