I follow Ed Zitron's Substack, and he is also a prolific Tweeter. He seems to be using Notes the same way he uses Twitter, for shitposting. I'm not sure that's really in line with the tone of Substack.
I actually thought that a newsfeed would be a good fit for substack, but looking at this i dont think i m going to use it. It should be simpler, a timeline of things i ve subscribed, with some threaded, sane comments. The medium shapes the message, and twitter's medium is just not a good fit for substack's message
I wasn't aware of any IP protection of Twitter's UI, which in one form or another has been done 100's of times.
I've been saying it since Twitter launched, but Twitter was/is just some folks stealing Facebook's status update.