[jacobr1]

That bothered me too. Trying a few though, it looks like they are 404s. Which is an interesting way to preserve a historical, but no longer valid link. If you are going to the trouble, it might be better to rewrite the links to point to Archive.org or something.

[dredmorbius]

Linking an archived copy (and proactively making an archive submission when initially linking, which seems to be an increasingly common practice), would be preferable.

[smeagull]

Ugh. Links are meant to live forever.

[dredmorbius]

Is/ought fallacy.

They clearly don't, despite 30+ years of whinging. (I've whinged plenty myself.) Preemptive defence is justified, necessary, and strongly advised.

The Web is not an archival platform, it's a publishing one. Each request is served in the moment it's requested, and absent specific measures for persistance can and will vanish at any time without notice.