It sounds like this failure led to the complete destruction of 3 online communities. While this might not be as bad as, say, a fatal multi-car accident on the highway, I bet it led to some heavy grief as users mourned the losses of their communities.
It might not sound like a big deal because it's just "a bunch of users and their posts/memes", but many people get the vast majority of their social interactions through social media. A sudden, total loss of such a site could be devastating to someone's social life. They might've lost contact with an intimate friend group they knew only via aliases with no other way to reach out.
Even for older generations like Baby Boomers, life is an increasingly online experience:
- How many senior citizens are reliant on Facebook for tons of their daily interactions with old friends? Probably a lot!
- Entire degrees from reputable universities can be earned fully remotely, and the transcripts, curricula, forum posts, and even proof that you earned such a degree exist in databases and distributed systems vulnerable to the exact same types of flaws outlined in the OP.
- Dating apps like Tinder / Bumble connect people who form long-lasting and loving relationships, and the sudden loss of such platforms could quickly end your potential lifelong romance.
- LinkedIn networks are of huge importance to some for continued, gainful employment. Are there memes there? Sure! But does that mean it's "just a bunch of posts and memes" whose loss would be fine? Hardly, in my opinion.