With NNTP, I could access the entire archive and it's separate from my email account. As far as I know, Discourse notifications only start from the date you subscribe, which makes it fine for new conversations, but isn't terribly useful when trying to avoid asking a question that's already been answered. Trying to be a good netizen, I search the archive first, but that brings me back to an isolated Discourse web instance.

Additionally, with NNTP, the "sign up" process is very low friction. With Discourse, I need to seek out each community separately. It's enough work where I'm unlikely to experiment with new communities.