Twitch’s new storage limits will purge huge swaths of Internet gaming history

I think this can be true for large swaths of the information that will be lost, but there's also a lot that will be lost that nobody is currently backing up. For instance:

1. Recordings people think are backed up simply because they're misinformed, only to realize all their old, say, childhood gaming videos are now lost forever
2. Clips that show damning behavior about a popular public figure that weren't caught before, but could become evidence in a future investigation
3. Clips previously thought to not be relevant, that then become relevant later on for some kind of general historical context (e.g. Campaigns started trying to figure out if something was in a game at a given time in a game with very little actual software backed up, devlog streams that contained lost features that could explain why a game then developed the way it is today, etc)

nothing of value will be lost

I'd argue the opposite: there's actually a lot of stuff out there that's actually interesting: old-school lets-players who'd have done actual informative playthroughs of games. It's kind of a dying art, but it's also exactly the kind of content that's going to get purged by this kind of action.

It's interesting to spend, say, 10 hours watching some guy play Sierra games and actually talk through shit about the game and whatnot, and it'd be a shame to have that vanish.

But not entirely unexpected since that's not profitable content in the way that the current morons babbling about bullshit reaction videos, totally-not-camgirls totally not showing their tits, and whatever other brainrot nonsense most of twitch is. (Also alt-right propaganda, but eh.)