"Store all your messages with a random site, what could possibly go wrong?"

We don't think of it as storage - although you can indeed use it as such. We think of it as messaging. Oh By gives you a way to send messages to unknown people at unknown future dates which don't require any special tooling (apps) to decode.

You can just take a piece of chalk and write your message on the sidewalk.

As for longevity, I think we have a good track record having run rsync.net for 16 years now.