The original claim I was disputing was the notion that once upon a time, running antagonistic and unfun games was the norm for most GMs and only rare GMs, well ahead of their time, were capable of identifying other ways to play. Along with this, I was disputing the notion that the majority of players would just accept antagonistic, unfun games and continue playing anyway. Finally, I was disputing the notion that recognising and calling out bad GMs is something we've only recently discovered how to do.
There's a couple problems here.
1. "Antagonist and unfun." Many of the people involved in this did not feel those two terms went together,
including a lot of players. They just thought a certain degree of antagonism, as long as long as it wasn't beyond bounds, was "how things were done". In part, this was because losing characters was almost unavoidable in OD&D as I referenced above; there was no unconsciousness threshold, and the hit point ranges for the first couple levels were so small for most characters that about the only way you could prevent character death was to have nothing that was threatening at all. This would have required sucking all the fun out of the game for the most part. As such it could be a pretty fine line between the two ends, and people were prone to tolerating a certain degree of falling off the edge, especially at the bottom end. As such the excessive GMs were thought of mostly as different in degree, not in kind.
2. The difference now is that modern GMs have a heck of a lot more tools to still provide challenges without skating over that line, and the focus of a lot of games is very, very different. As noted, before the entrance of the Dragonlance setting in the mid-80's, D&D particular tended to have a very, very different tone; even if people wanted games focused more toward high heroic games there just wasn't a lot of support for it. But that slowly crept in mechanically, and because of it, in how people tended to run games.
I really think its easy to understimate how much the very wargamey roots of D&D in particular impacted the way the game played for about the first decade. Antagonism wasn't viewed as a downside because that's what a lot of people coming to the game expected; the GM was providing a challenge for them, so
of course he was going to be antagonistic. They only objected if it felt like he was abusing his power. The fact the presentation of the game sometimes muddied that, but it was that abuse that was resented, not the antagonism as such.
It was just that the more it swung into the "fantasy protagonists with dice" view, the harder it was to use that as the standard, so it progressively became less and less appreciated. And there's some remaining conflicts between those that can accept that and those that can't.
