Does London System take skill or any theory? what do you think

Releasing the tension early sometimes is stylistic or is sometimes done for practical purposes. Eg Karpov typically released tensions early ( while eg Fischer typically retained it longer ).

We just can't know what the outcome would had been if Nepo played another line.

This is true, but in the London, it's an inaccurate style choice similar to the Exchange French.

This is also true, he likely would have lost as well, but I maintain that he'd have had a slightly better chance from the start of the game simply due to having more threats available to him.

It was responding to a conversation I was a part of where I said Qb6 was the best line and he thought I didn't have the right to say that because I'm not as good as Nepo. This is what was implied.

I responded by providing my evidence and reasoning. I wasn't getting offended. That's just your perception.

Okay. I didn't have all the evidence, I apologize. I do believe your reaction was slightly harsh still, but at least I understand it now.

I looked at this with my coach and I actually avoided the line because white could put his knight on e5. But it really doesn't do much, and white doesn't have many good attacking plans anyways while black does have some clear ideas on the queenside.

All cxd did is fix the pawn structure to a reverse Carlsbad, this is neither good nor bad. The plan with a4 ( ..a5 in the normal Carlsbad) is also one of the 4-5 classic plans in this structure to counter the minority attack, it's not because of any concession by Nepo. Ding "just" played very accurately, and kept control of the position, while Nepo didn't play accurately after the opening. The opening was largely irrelevant, as was the early release of the tension.

We can't know how the game would had ended if they played differently, he may had lost , drawn or won, who knows..

It was some rapid game with Kramnik, and Dubov was super impressed because he thought "white had nothing" too (and the engine is saying equal), but then Carlsen beat Kramnik effortlessly... but this was a different position of course (slightly different minor pieces and structure). Your game may have actually been equal after d5. I'm just saying it's something I became aware of after this last WCC game... where again, black didn't seem to do anything so wrong, but white made it look easy.

But sure, looking at your position on my own, I don't think it's anything special for white, and black has his own ideas.

FWIW I'm trying this for now

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Not sure if this was already pointed out, but I saw some people asking why Nepo didn't play 5...Qb6, and why he chose 5...cxd4 instead.

It might be worth pondering that Ding often plays 5... Qb6, when he has the black pieces against the London.

Nepo, having studied Ding's games, would've known this. And this would've almost certainly been on his mind, when they reached that opening position.

In match play, there's going to be a lot of psychhology - back-and-forth parrying, based on each player's knowledge of the other's history and preferences ...

We don't see that, as spectators. We just see the moves. But there's a lot of subtle maneuvering happening, beneath the surface.

When a SuperGM chooses a certain opening line, it's usually far deeper than him just thinking, "What's a good move here?" It's more like: "Hmm ... this brings to mind a game my opponent played 4 years ago, in Riga, where the endgame led to a favorable pawn imbalance for black ..."

I didn't see anyone point it out, so sure, it's worth saying.

Here or in a different topic someone said something like "I guess Nepo didn't study the London" lol. These guys knew more London theory 5 years ago than I'll ever learn in my life. By the time they walk into a WCC match, they're like living encyclopedias of chess. Not the opening, and not the result will have anything to do with anything an 800 rated player could possibly guess.

... and obviously they don't know everything. Surprises happen all the time, which is why they have to be so well prepared, but not the freakin' London, lol.

I remember one time at the club a beginner was watching my game, and pointed out I didn't need to think so long since I could easily recapture my knight two different ways... yes... I didn't think I was a knight down... I was worried about the position 5 moves from now

And like you're saying, they're worried about "oh, this opening choice led Ding's opponent to have a difficult endgame 5 years ago, maybe I don't want that line."

... still, with so many decisive games, I feel like there must have been some poor decision making... even if I have no idea when and what it was.