I'm not seeing that from the article. It's more "he stole the idea from this guy that created the idea via various games."
Kinda sounds like co-writers bashing on each other years later because they took pieces of each others works and then published it.
Gygax read through Arneson’s notes. “Halfway through the reading,” Kuntz said, “Gary… nonchalantly said, ‘This needs to be rewritten.’ Not one nice thing to say about Dave, the adventure the rules. This is when it all switches.”
“He was jealous. Just stone-cold jealous.”
I mean, that's fuzzy history, they may think he was being a dick when he was simply stating "if you want to sell this, you'll need to rewrite it to make clear/etc." which would make sense as games designer.
“Gary at this point is wanting to desperately latch onto some sort of game to make himself a success,” said Stormberg. “He really sees the potential in this and latches onto the idea to make it into something that can be shared. As it is, it’s something that can be enjoyed when Dave runs a game for his friends. But until Gary Gygax gets a hold of it, it can’t be shared with the masses.”
“It was intuited and put together by the genius Arneson, like a mad alchemist,” said Kuntz. “If there’s any good thing you could say about Gary, you could say he knew when to move on a good idea and had the wherewithal to make it happen.”
Yeah, this is a game designer wanting a name-recognition product and just "stealing" the idea from someone else. This happens nearly all the time, and sucks, but I don't think it makes him a "dick" for doing that. Like the second paragraph says: Arneson was the idea man, but he didn't see it as something that could be "sold." Gygax did.
OHHHHHH, ok, the last like.... 20% of the article starts to go into Gygax like publically freaking out about the company he created being "hostile takeover'd" by the other folks.
“The biggest problem with the whole Dungeons & Dragons thing is the desire to claim ownership for the invention of D&D created a schism between Arneson and Gygax,” Morgan said. The two even ran their own D&D games differently in 1975, Gygax wrote in an issue of Alarums & Excursions. “Dave and I disagree on how to handle any number of things, and both of our campaigns differ from the ‘rules’ found in DandD.”
Arneson had designed a way to organize the imagination and foster communal storytelling; Gygax had designed a way to ground it in wargaming traditions, package and sell that. Today, the Chainmail-inspired rules Gygax mixed in with D&D’s prototype are quite altered, while Arneson’s initial role-playing conceit, and the variability of rulesets encouraged by his Minnesota friends, is what defines the genre.
In the end Arneson won out because rules-crunching/wargaming isn't something people want to do when they role-play, they just want to get into cool situations and then try to roll dice quickly to get through the combat scenarios.
“I don’t think it was his plan as a kid, as a young adult, to become some entrepreneurial game designer,” said Malia Arneson, Dave Arneson’s daughter, of her father in Secrets of Blackmoor.