How is it a whole lot of effort to leave? Maybe I misunderstand your point, but you never have to come back to Slack again, if you don't want to. If you meant that there are lots of helpful people here, and that is tough to leave, then I agree completely 🙂

It's effort to leave here in the sense that if I don't come back to slack again, I've still given an email and can be counted in a database as being a user.

Removing myself from that list would take effort, whereas IRC's lack of such a list means that users were counted in a more ephemeral & ad-hoc manner.

The separation of invitations for each domain means that getting off those lists scales linearly.