And for product documentation for version n-2.x, it's easy enough to see the use case for why a customer might need it. (e.g. they have some other product that's version locked to it) But there is a ton of collateral, videos, etc. that companies produce that get stale, musty, or just plain wrong and if you leave them all out there it's just a mess that's now up to the customer to decide what's right, what's mostly right, and what's plain wrong.
So, while there may be some historical interest in how we were talking about, say, cloud computing in 2010, that's the kind of thing I keep in my personal files and generally wouldn't expect a company to keep searchable on its web site.
> But there is a ton of collateral, videos, etc. that companies produce that get stale, musty, or just plain wrong
That 2017 product roadmap slide saying "we'll deliver X version N+1 by 2020" gets a bit embarrassing when 2023 rolls around and it is still nowhere to be seen. Maybe the real answer is "X wasn't making enough money so the new version was cancelled", but you don't want to publicly announce that (what will the press make of it?), you just hope everyone forgets you ever promised it. You can't get rid of copies of the slide deck your sales people emailed to customers, or you presented at a conference, or in the Internet Archive Wayback Machine – but at least you can nuke it off your own website. Reduces the odds of being publicly embarrassed by the whole thing.
Or your 2011 presentation about cloud computing didn't mention containers. I'm not sure it's embarrassing any more than a zillion other forward looking crystal ball glimpses is embarrassing. But there's no real reason to keep on your site unless your intent is to provide a view into technology's twisty path or the various false starts every company makes with its products.
So, while there may be some historical interest in how we were talking about, say, cloud computing in 2010, that's the kind of thing I keep in my personal files and generally wouldn't expect a company to keep searchable on its web site.