Author here! If you 100% need E2EE for your notes then not using Supernotes is actually our recommendation as well. But as I tried to show in the post, it's hard to do and arguably even harder to prove that it has been done correctly. And E2EE not done correctly might as well not be done at all.

And yep, partly it is that don't have the time to dedicate to this. There are so many other features that I think would better serve our users than E2EE, so we're prioritizing those for now (table stakes in the notes game are very high). But if I had infinite time at my disposal, I absolutely would add some form of E2EE – though still not sure I'd make it the default as again, there are some things you can't engineer your way out of when you add E2EE.

The one that is most on my mind probably being irrecoverable data loss. If watching the cryptocurrency space over the last few years has taught me anything, it's that even if you beg people to take good care of secret/recovery keys, frequently they don't. And that's for stuff you can sell for actual money.