I have an expert level rating. I agree with everything in the content. My games are very similar to what he describes. I have not memorized many openings. I just know a few moves in common openings and how to respond to a few quirky responses to them. I want to get to the middle game or out of my opponents memory as quickly as possible. I also sometimes deliberately make some opening weak moves to get out of opponent's memory.
One main thing I found in my experience is, majority of the games in amateur level are decided by blunders. I am not talking about small positional bad moves. These loose pieces are get mated in one move. If you are an amateur first focus on avoiding them by studying tactics before memorizing anything else.
I am a terrible player, but I absolutely love playing. One of my biggest problems is making a move and them immediately seeing the err of my ways. It's beyond bizarre how quickly I'll realize what a shitty move I have just made right after I take my hand off the piece.
I'd say I have a few decent tactics that I sort of lean on, but, like you pointed to, if my opponent does something to break me from that memory, my game is shot and I'm flailing around trying to recover (which rarely works).
Not sure if I'll ever dedicate enough time to reach "decent" status but I definitely enjoy the game.
I am also an expert player, and agree with most of what was said, but I do think I should point out that this player's style is not the only strategy ("My strategy is usually to throw lots of pieces at their king and hope they die or I can win some material"). Personally, I prefer more closed/quite games, so most of my thinking (even in the middle game) is about how to achieve a favorable endgame, and win from there.
EDIT: I dislike studying openings too, (I started playing 1. g3 to avoid theory while still getting into some fun positions)
I was surprised to see nothing about pressure and the whole pins/forks/discovered attack options that restrict your opponent's choices.
Beyond the basic "stupid mistake" level of play, chess centres around forcing your opponent into a situtation where they have two different risks that they need to defend against and only one move to do it, while not allowing your opponent to do the same to you.
I'm a pretty bad player (mostly playing with my 7yo son), and I totally agree about the blunders thing. The most effective way to learn how to avoid them IMO is to play a lot against good algorithms - that might not play hard tactically at the easier setting, but never make stupid moves or fail to detect my own stupid mistakes. You can't win these games by lucking out :)
Not all computer chess programs behave like this, some of them, at the easier levels make stupid mistakes, or don't take advantage of my own oversights. I try to avoid these. Playing against other amateur players that don't always take full advantage of your stupid mistakes doesn't train you well enough for this.
One main thing I found in my experience is, majority of the games in amateur level are decided by blunders. I am not talking about small positional bad moves. These loose pieces are get mated in one move. If you are an amateur first focus on avoiding them by studying tactics before memorizing anything else.