One of the common complaints of TSR in the 2e era was their judicious use of so-called "metaplots" - essentially, keeping the game world's timeline moving and often changing established settings with new product updates. Often, these changes were brought about through actions in novels, although there were also game line products that could change the setting as well.
In some TSR settings, these product updates would scare away some of the casual gamers - it's hard to keep up with a setting, and they didn't want to spend the necessary money to follow a game's "canon". Many gamers would avoid TSR's settings because they didn't want to see their game be declared obsolete through some change made by TSR (silly thinking, I know, but a lot of gamers felt that way!)
Here's the thing.
It wasn't just TSR that did it. In the 90s, most of the major companies had metaplots (often tied to novels or even TV series!) in their RPG lines. And a lot of non-D&D games still have ongoing metaplots.
<SNIP>
Anyways. It's just a pet peeve when people point at TSR and mention how awful metaplots were, when there are whole lines that did it... and still exist today.
Is this really new information? I think most of us that were playing back then were aware of it. I imagine people who hated it in TSR game lines mention it because they hated it in TSR game lines, regardless of the existence of other products doing the same thing. I don't know that I would say TSR created it, but maybe some people blame them for it. White Wolf was more widely known for it at the time IME.
As far as the hatritude towards them, I always thought most of it was overblown. I didn't like what they did with the Greyhawk Wars but since earlier campaign material was dated 576 and the wars were 591 I could set my games in between those times and not really have to worry about stepping on canon if it mattered.
Same thing with Battletech - the earlier material was set in 3025, the clans invade in 3050 so there's 25 years to work with before canon becomes an issue and the game technology changes. Unless your campaign was set in 3048 (probably on purpose to play through the invasion as it happens) then I don't see how one campaign could be impacted by it a whole lot.
Star Fleet Battles has had the same thing since 1980 when X-Ships were introduced to the game- vastly different technology enters the game universe at point X and games set before or after that point are dramatically different.
Heck ASL has had the same problem since before that - the Russians get a ridiculous powering-up about 1943 that really changes the game and upsets many fans, especially those who play Germans
A lot of the complaints about metaplot spring from just having a timeline. Unless the game is set at the end of that timeline, then you're going to have some issues with characters not having an impact, events happening offstage, countries springing up or disappearing over time and other related issues. I thought Shadowrun handled this well as every new edition of Shadowrun was set a few more years in the future -2050, 2052, 2060, etc. I assumed this was to not step on the toes of existing material and existing campaigns. If you keep track of time in your campaign, then it seems unlikely most of them will burn through 10+ years of gametime that quickly, so no conflict. If you don't keep track of time then it's still not a problem - your campaign is in "the time before" and that other stuff happens later.
I also think a lot of it springs from the collector/completist mindset more than a few of us suffer from. Just remember that collecting it, using it in a game, and liking it are 3 separate things. I have supplements that I don't like for games that I do and I suspect I am not alone.