Beginner advice: Do NOT study openings (game included 2100vs2100)

Ok it was ingenious sarcasm on you part. Yeah im like sheldon in picking that up. And btw titled players often pick an opening according to a plan, sometime you wonder if amateurs a even capable of formulating and executing a coherent plan. You see 2100 players sacrificing structure for activity and don't even play active.

I have to agree with @MeWantCookieMobile. Often when weaker players say "I lost because of lack of opening preparation" what they mean is they blundered in the opening and so they lost. While that could have been prevented by memorising a lot of opening theory, it also could have been prevented more productively by training yourself in tactics and pattern recognition. The well prepared 1700 will lose to an unprepared 2000 9 times out of 10, simply because he will play far better in the mid and endgame and he will blunder tactics much less often.
Strength always trumps preparation, especially if your goal is to ACTUALLY become a better chess player, rather than just win some club games.

And more to the same point, let's hypothetically say that you are a 1700 player who is the most knowledgeable opening expert in the world. If you are not that good at calculation and you miss tactics often (which in this case must be true), at some point people will just figure you out and start playing random garbage-y openings against you, like the one I played here. They'll let you have a slight edge out of the opening at the cost of getting you out of your deep and extensive preparation and then you will just hang pieces left and right and get checkmated.

On top you have to rely on other, and wouldn't know if bs or not. But tactis training stays with you.

Beginners are advised not to learn openings by heart because that ain’t „true chess“. Instead they are told to learn endgames by heart because this is considered „true mastery“. The heck?

My suggestion: expose yourself to as much decent chess content as possible and let your brain work and compose. No matter whether learned by heart, openings, endgames etc.

Gather chess chunks, many of them!

@MeWantCookieMobile take this game for example:

If I have known the theory, I wouldn't have played b5-a5 and get in the disasterous position with weak c-pawn. I would also know that playing Ba6 in this kind of position is not the brightest idea. It wasn't lost from the opening, but it was very difficult to find the right moves, while white was playing naturally and with comfort.