I remember explaining D&D to my brother back in 1980. I'd started playing in '78; but this always happened off camera (mere coincidence because we did share friends), so he didn't have questions until I got a Holmes Basic set for Christmas, forcing him to reckon with an emerging phenomenon. His first observation was that the DM could do what they wished, and there wasn't much anyone could do about it. Unfairness loomed because (obviously) we humans are natural-born assholes largely helpless to resist our nature...
It's a fair assessment. I've seen all too many misuse their authority, mainly the immature, a quantity in no short supply among adolescents (and too many adults). My only defense, unassailable by every measure, was that in a game of ongoing adventures, killer DMs would quickly find themselves without players. All this, and several months before I got my first Dungeon Master's Guide and read Gary's take on deficient DMs. I pitched this in terms of game balance (and whatnot); but at the end of the day, who likes an asshole?
GMs are the usual suspects given their obvious power. But players can also be a problem, albeit differently. I'm not talking about those too shy or insecure to contribute. Friendship and understanding goes a long way. Nor am I talking those of evil alignment, sanctioned by the rules and allowed to exist. OD&D had its Conan rule, which I'll employ. Assassins and similar miscreants shouldn't want to attract the wrong sort of attention, so this tends to sort itself naturally once the city guard and/or church (or archmage) gets involved.
So the good news is that gaming is social. That's its biggest strength, and one exceeding the power of mere storytelling alone. But the bad news is that gaming is social, meaning the experience is subject to the social contract - and easily derailed without the people skills no rules can possibly provide. Not the modern iteration, mechanically structured around the concept of fairness, and certainly not the free-kriegsspiel revolution. Only people can deliver that, so it's up to us whether my brother's observation becomes a dire prophesy...