Prove email and phone are required in online services

[i_see_things]

I'll pay you $160 if you can prove mathematically that the only way to offer online services without spam is by requiring people to provide an email address or a phone number. That would be an interesting result.

If this can't be proven mathematically and you are an online service then please answer: why must online services require users to provide an email address or a phone number to get service? Why is no other option offered to the user?

Why is it impossible for a human to use online services while not having an email or a phone?

[mattl]

What would you use instead of an email address to identify a user upon registration? An email address is something most people have and its a workflow people are familiar with.

[hitpointdrew]

I think the point is NOT to identify users, but only to not have spam/bots. Unless it’s a paid service, users should not have to identify themselves. You can keep out bots with CAPTCHA.

[jaclaz]

>Why is no other option offered to the user?

Name these other options, please.

[i_see_things]

One is the same option you used to signup for HackerNews: a new username. Not a pre-existing email or a pre-existing phone number.