Why do most LLMs insist on a login, even for a free trial?

I entered a question to try it, but as soon as I hit enter it wants my phone number for a login. No thanks.

Think about it for 2 seconds.

There's many obvious excuses ...

Are you claiming a necessity ?

Free use without registration -> free to anyone and anything -> easy to abuse at scale, with no way to restrict use.

You can limit it a lot to minimize the abuse. In free entrypoint, set token and context limits to be very small. Limit to 2 prompts per IP or something every X hour. That is already a substantial limit where bypassing might not provide much benefits.

Residential proxies are too prevalent for IP address limits to work effectively.

Is there some public research that how often, for example, people download malware that allows this?

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