Ask HN: Where are all the old Show HNs?

Searching for "Show HN" posts (using hn.algolia.com) reveals a sad story: Many of them are gone. I wonder what happens to Shown HNs, esp. the ones that are featured on HN, but then end up not existing anymore. Is it the server costs? Do they sell to other companies? Did the developer pass away and so did the link?