This is a pretty funny meme, especially the "quote" at the bottom. (Not sure I've ever put air-quotes around the word quote before. Seems very meta.)
Funny as it is, from a more realistic standpoint it is clear that Gary was in an arms race with players from 1974-1980. Given that his players were constantly escalating their game and using (abusing?) magic items, some of the blame for "gotcha" monsters has to go on Gary's players as well. For every rust monster there's a player who loads up a mule with 10 shields and 20 flasks of oil.
You know about the module S1: The Tomb of Horrors, right? We've all seen this beautiful Erol Otus (no relation) image? I have to wonder why this was the back cover instead of the front!
Anyway, this dungeon has the reputation of being a stone cold killer (puns intended). But of course it's not an example of Gary writing a dungeon just to be mean. Or ... well ... it is, but you have to know the context. Gary wrote it specifically to test high level players. He wrote it for convention/tournament play (not to kill off long-lived beloved home-group characters) and he wrote it after his player's boasted they could handle anything AD&D had to throw at them. He did nothing to hide his mindset when planning/writing S1: "I admit to chuckling evilly as I did so." And he designed it specifically to challenge the likes of Rob Kuntz' Robilar and Ernie Gygax's Tenser, characters that had been around, literally, longer than D&D had been in print.
All of this is to make a point I think we all already knew, but popular, revisionist thinking likes to paint Gygax as a mean-spirited character killer and an autocratic GM. He was some of that, but his players were murder hobos. And it's a chicken-and-egg argument as to which came first or if either cared. I don't hear those players going around crying about Gary being too tough or unfairly wiping out their favorite PCs. Which means all of the reactive games designed around a "non-adversarial" approach to D&D, good as they are, were either solutions in search of a problem and/or set up Gygax and Oe play as a straw make themselves look good. Phah, I say!
If you go looking for advice from Gary about how to kill PCs or make their lives hell, you will find it. If you go looking for words from Gary about their being only one way to play D&D (his way), you'll find them. But the opposite is also true. I can easily go find places where Gary suggests alternative challenges that are less likely to kill characters and places where he told you to make it up and have fun rather than writing to him for answers. (Both of the ones I'm thinking of right now, by the way, were in volume III of original D&D).
[In case this is starting to sound like a "get off my lawn" rant, please understand that my intended tone is an equal mix of laughing over some of the craziness in early D&D and some of the craziness in modern thinking about early D&D. I don't take this stuff too seriously, but I worry that the jokes and characterization of early play are somewhat misleading. So, I'm also trying to make a point, which is...]
Have your fun, but be careful how you characterize play from the 70s and 80s if you weren't there or haven't done your research. And maybe don't be so hasty to discount adversarial style play if it is conducted in a spirit of fun and fairness. Not all players want to walk trough a heroic story of their own invention or the GM's. Some want to explore, face challenges, and fully experience the outcome of their choices (rather than having them molded back into some predetermined course of events).