As can be seen from the webpage archives, the popular french musician and conductor Frédéric Chaslinpurged every track except one of his SoundCloud repository early this year.
Some of the tracks are covers of classic musicians like Beethoven, which were played by an orchestra that was directed by him. He uploaded them in early 2013. According to description, these played on radio! His exact iteration of some of the tracks like the fifth symphony currently are nowhere to be found after having been on air for nine years (over 3.000 days) with over 700,000 plays and over 15,000 times favourited.
It used to be the first result on SoundCloud for Beethoven's fifth symphony (archive), meaning it was the most popular iteration.
Spontaneous takedown by uploader is a risk not to be underestimated to any online media. Statistically, it appears to be very high up in the "leading causes of fatality" for web media.
One of the best projects in existence. They are among the greatest saints of the Internet. However, the Wayback Machine very likely does not cover 100% of posts, and page text is not searchable (possibly because they store them using strong compression), whereas an archive file with all user contributions is both searchable and has full coverage.
Exemplarily, Wikipedia regularly generates compressed archives of their historically significant content, meaning if it shut down or had a long-lasting outage, contributions would not be memory-holed.
I don't expect the Internet Archive to shut down any time soon (which would be against its purpose), but our contributions are likelier to survive for decades if distributed through a peer-to-peer network through archive files. The Internet Archive has been legally attacked by greedy book publishing houses for doing the right thing in 2020, meaning we can not depend on one organization to keep our history intact eternally, even if it is them.
In the past, I have referenced and contributed to sites such as Yahoo Answers, which disappointingly ended up shutting down with little notice after operating seemingly well for a long time, i.e. over a decade.
I don't expect it to happen here any time soon, but in the case that this forum which stores historically significant content ends up shutting down at some point in future, I would like to ask whether it has a backup plan. Since text compresses efficiently, will a compressed archive of users' contributions be released? And how long in advance would there be a warning?