I wonder how difficult it would be to make a website that, instead of serving 404's, a model does a semantic search using the nonexistent URL to come up with a URL that actually does exist and most closely matches the "intent" of the invalid one.
The safe thing to do is return a 404 with a few suggested links.
The problem is that "guessing" the intent of the URL will have unintended consequences. A URL will no longer be guaranteed to point to what you think it points to. This fundamentally breaks the assumption of what a URL is.
How could this happen?
1: Site creates article foo.com/chocolate_bars 2: Someone accidentally links to foo.com/cocoa_bars, which serves foo.com/chocolate_bars 3: Site creates article foo.com/coco_bars 4: Now foo.com/cocoa_bars serves foo.com/coco_bars
But agreed this would not be good general practice. It was mostly a thought experiment.
The 404 communicates to search engines, archive.org, ect, that the link is broken.
The human-readable text on the 404 page can contain a link to the correct page. It could even contain a few paragraphs too.
Should get close enough to your original idea without too many unintended consequences.
(not being serious here)
This is what it generated for one of the non-existent articles