1. Watching so many things being built in real-time, both client-side & relay-side. Also, reading notes in different languages
2. Search & discoverability, learning curve for new users
3. About 6 months back
4. Amethyst & nostr.band
5. Spam
6. Twitter had an element of serendipity in surfacing stuff, which isn't there in a follow-based (or even WoT TL).