Depends. In some ways you are correct but in other ways not so much. We like to think in the digital age once its up, its up forever. In theory yes but in some ways no since we have already seen in recent memory. Hell the popularity of lemmy and the fedeverse was kicked off because many of us left reddit, lead to many of us basically deleting/editing our prior comments. Someone can possibly have a snapshot of it but the chances of it are pretty small for some weird random obscure post on a forum. Our reliance on free services can easily lead to something disappearing as easily as it appeared. Hell we are seeing some youtube videos basically disappearing over fears of Ai scraping and it can happen abruptly.