Whether you are part of that subset is entirely up to you. So I frankly don’t understand your argument.
(note: Thunderbird isn’t the only client that allows threaded display, it’s just the one I’m using as an example)
I don’t know what “e-mail first” means. What I know is that e-mail as a communication tool isn’t going away, and people will still be required to master e-mail in 10 or 20 years.
I remain to be convinced that it’s gonna work on, e.g., a PEP discussion, where usually the problem is not someone veering off-topic to talk about e-mail clients.
I still stand by my example: as a moderator, can you try to cut Python Governance Electoral System in several independent Discourse topics? If you think this is too tedious or too much work, then you’re making my point.