Is stuff online worth saving?

Yes. Sometimes when I'm doing research into recent history of why certain technical decisions were made, and the arguments for or against, I find archive.org invaluable for piecing a line of thought back then. Recently, this was to look up what the debate between React's Functional components vs Signals was.

Also, it's helpful to get perspective on the attitudes for or against a new technology in recent history. I remembered there were people that said "If you aren't writing a kernel, you don't have their problems, so you don't need git." Turns out that's not true. Now that git is everywhere, it's harder to remember whether or even if there was pushback against it.

This was written about the insights from using git that he needed to highlight to people back then. https://keithp.com/blog/Repository_Formats_Matter/

I often reference it, and if it wasn't still up, I'd have only web archive to rely on.

So for me, lots of stuff I look at online (mainly blog posts) are worth saving. Sometimes, if the discussion is on a twitter thread, that too. Which makes me fear for the day Microsoft decides to do Github in, and we'd lose all the issues and comments.