This is the way HN works. It's the way most websites used to work, until maybe 15 years ago, give or take. Today almost all sites ask for verified email addresses, but this used to not be the case.
Besides the commercial value of having user email addresses, I think it's mostly done for the webdev's ego:
> Users need to hear about my new update! (Because if I don't spam their inbox, nobody will notice or care about the thing I just did.)