They work for me ;)
There are several links around that will return a 404 for you, but work for others. I'm sure you have noticed by now that we have a reputation based privilege system, you get access to a variety of tools & toys as you earn reputation. And when you reach 10,000 you will be able to see deleted questions, if you have a direct link to them and the links in your profile you point to would work just fine.
A 404 error does not necessarily mean that there's nothing there and there will never be, just that there's nothing there right now. Let's see how rfc2616 describes it (emphasis mine):
10.4.5 404 Not Found
The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address. This status code is commonly used when the server does not wish to reveal exactly why the request has been refused, or when no other response is applicable.
Simply put 404 is the preferred error code when something is not there but may be available in the future, and in our case that means when you get some more reputation points. But why have the links at all in your profile? Well, three reasons:
- It would be an overly complicated solution to remove all the links when you don't access them, and the benefit (if any) would be extremely small. Reputation is fluid, I was jumping over and under 10K for a couple of days1 and it would be a mess to update every link every time I got or lost access to the 10K privileges. Especially the profile page is a very low priority aspect of the site, and is cached aggressively, showing the links only when you can follow them would require the cache to be refreshed every time you get the privilege or lose it. That'd be a lot of work for nothing...
- Moderators and diamonded Stack Exchange employees can see your profile the same way you do (the only exception being the votes tab), so if the links updated as you gained or lost privileges, another snapshot of your profile would be required for all of us that can see it from a moderator's perspective.
- Most of these links lead to deleted questions and answers, and in case you'd want to make a case against the deletion, having the link would be extremely helpful, even if you can't actually see the deleted posts. Others can follow it and get a better idea of why it was deleted.
Now, some of the links are indeed removed, and it's a lot easier to do that on just the delete event than to scan back all actions the question generated and update them all. A small inconsistency, but a harmless one (imho) and I think the easiest solution to it would be to just not remove the links (but let's not poke the bear on this one). Worth noting that this is a rare case where the question was deleted only a day after it was asked (yes, it was that bad), typically we wait at least a month before deleting closed questions, and if that had happened you probably wouldn't even notice (the events would be far apart in your profile).
I'm marking this as [status-bydesign] as you predicted ;)
1 That's a theoretical example, as a moderator I have access to all toys, regardless of reputation. That said I would like to take this opportunity to thank the serial voter who took me over (and under when the script run) 10K a couple of times, that was a blast :| Serial voting is a bad idea in general, but it's exceptionally moronic when you are serially voting one of the very few who have access to tools that detect abusive voting patterns and can find out who you are.