This is very much a multi-player thing, but man does this also screw with you in a single-player game. You just don't notice it until you decide to let others watch you and they call you on it. The problem? A lack of focus on the task at hand. Getting distracted is no good, no matter the situation. It's even worse if you also don't read the manual, so you don't know what you're doing.
You've all met this guy. You're playing a game, and he's not paying attention. His turn comes around, and now he's asking what's going on before making a decision. That may not sound like a problem, but that time wasted adds up fast. In the workplace, this is what turns a short briefing into a three hour meeting. At the game table, it's what consumes the evening you have to play a tabletop RPG or a complex boardgame so that little or nothing gets done. Online, it's the guy who doesn't read the strats and doesn't pay attention to the leader calling the shots, making what should've been easily done into a time-wasting trainwreck.
I'm over 40 now. I don't have time for this shit anymore. I routinely kick these boat anchors out now, and I don't give two shits about people whining at me being a hardass over it. I value my time greater than all the gold in the world. The surest way to piss me off is to disrespect my time like this, and putting boot to ass reliably solves my problem with such chodes.
I've often made the explicit comparison between tabletop RPGs and holding a job. (I also do this between being a top-end raider in a MMORPG and holding a job.) Sometimes this is not a good thing, but in this respect it most certain is a good one: you had better respect the time that others pay to play the game.
Showing up on time, prepared, and ready to go is the goddamn norm and it should have been drilled into you as a child. Giving your full, undivided attention to the task at hand is the goddamn norm and it should have been drilled into you as a child. The fun is in getting shit done, and focusing your attention is focusing your energy; the more the group maintains that focus, the faster shit gets done and therefore the more shit gets done within a given interval of time. The same "focus fire" principle that applies to martial arts and warfare is universally applicable, and you should know that by now as an adult.
And yet, one need only watch some livestreaming gamers on Twitch (et. al.) to see that plenty of adults never got the memo. *sigh*
I'm not your father or your doctor. I don't care why you can't meet basic adult performance expectations. All I care about is that you meet them, and if I find that you're unable to do so then you're gone. I will boot your ass, and whining or backbiting after the fact will make that booting into a permanent, lifetime ban. Check yourself before you wreck yourself.