The only one that has died since the end of Digg was Vine, and that was partially just because its owners didn't really care about its fate anymore.

Vine was killed by facebook & its regulatory capture. Otherwise it would've killed facebook and we never would've gotten tik tok (for better or worse).

FB, the gram and now twitter are dying. Just because they still exist doesn't mean they're not on their way out. Anyone with accounts on the first two can tell you that the number of active users on their feeds has been the same people for 5-10 years and are dwindling (and the feed of the third is lmao since boosting paid user content). Their traffic numbers might look fine but that's because they lie about those numbers and they make it impossible to delete accounts.

Most importantly, it's been 15 years since any of these companies couldn't get free financing. Often a focus on profitability results in misplaced user-hostility over short-sighted moves, which is what killed a lot of companies in 99 and again in 2007. We just haven't had a financial climate that requires it since. Hilariously this climate would make it a perfect time to take twitter private to push it past the other two and tik tok but it got bought by the worst failson the world has ever seen.

Don't mistake still existing for not being dead. Digg.com still employs dozens of people, that doesn't mean its been a useful link aggregator for the last 12 years.