We love Nostr as a publishing platform that offers unparalleled censorship resistance. But NIP44 does NOT provide most of the important qualities of e2e encryption:
- break-in recovery.
- repudiation (deniability).
- visibility of connection graph to observers.
- fixed message sizes (although it can be provided by the specific app)
- resistance to Shore algorithm (PQ encryption).
It's unclear whether it provides forward secrecy, but the spec implies that it does not - I might be wrong here.
We wrote this post about the qualities of e2e encryption and why they are important: 
SimpleX Chat v5.6 (beta): adding quantum resistance to Signal double ratchet algorithm