I’m mostly on board with you. I’m firmly in the camp that states “dice are there to make noise behind the screen”. And I’m firmly in the camp that states that the DM and PCs are not on opposite sides, with the players trying to “win” over the DM and the DM trying to kill them at all cost à la Gygax. That’s just dumb (and the DM will win). We’re all cooperating to tell a cool story, investigate cool crimes, summon cool eldritch abominations wot man should not wot of and so on.
Bearing that in mind, in the overwhelming majority of cases I won’t “cheat”, either because the results of the dice roll don’t really matter to the action at hand or because I don’t have a strong opinion on the result of a given course of action - whether that kobold hit the fighter for 5 HP or missed isn’t going to be remembered in the Great Book of Memories ; and that NPC may or may not see through the PCs lies - that’s why we have portable random number generators on the table. I also won’t **ever **cheat when I roll on behalf of the PCs (such as when rolling their perception, sense motive etc… ; I prefer to jot down their scores and do it on my own than call “roll Perception”, because of course when you do that the players know there’s deffo something to percept at ; and even if their characters don’t hear shit they’ll go into paranoid mode. I’ll routinely make fake rolls to hide the real ones, too).
OTOH, if a roll of mine would kill a PC for no reason and no fault of their own (i.e. oops, that ogre crit for all the damage, as opposed to “oops, you took 40d6 of falling damage because I TOLD YOU THAT CHASM LOOKED TOO WIDE TO JUMP”) I’m not above forgetting the crit. I sometime kill PCs, but I’d rather they go out with a story and a bang, y’know ? OTOOH, I’m also not above saving a Big Bad that I intend to be a recurring guy they’ll love to hate just because somebody rolled a 20, or because my guy rolled a 1 on a dumb save-or-suck he could only have been affected via said 1. It’s not kosher to turn the villain to stone while he’s dramatically monologuing ! Have a little class !
Unless it’s funny, of course.
None of my players ever complained it wasn’t “fair” to them. It’s understood that sometimes the DM gets to say “shut up, it’s magical” for the purpose of storytelling. There are games where narrative control is shared with the players and games without DMs at all ; but in D&D-likes (and similar “traditional” RPGs), the DM is the final authority on what goes and what doesn’t. And if they don’t suck, they’ll only use this ultimate cosmic power for good.
Or when a player is being a jerk and needs a Lesson :D.