... but depressing for 'owners' of unpopular threads

More seriously, wouldn't this be difficult to implement reliably (e.g. excluding multiple visits by the same visitor) without forcing the acceptance of cookies?

FT, unlike ebay, works even if cookies are rejected, and this is a feature appreciated by some privacy-conscious users, myself included.

Leaving one's cookies on a public, shared, or company machine is not a good idea, and many users do not know how to delete them.