Spam problem is absolutely miniscule in comparison with the forthcoming. GPT-N running in medium-sized datacenter would be able to outargue 90% of people on any topic. Imagine each person in the world been assigned his own personal team of propaganda agents. The defence would be an independent ID system. Something historically done by governments only, with a sizeable infrastructure.

I feel like the best way to filter spam is using information content. As it turns out, nobody is handing out $1,000,000 for free no matter how nicely they write the email.

Isn't that the whole point of gating it behind an API?

There will always be a spammer with connections to a large company or university.

It's not only having the connection, it's that they are presumably able to audit your usage and reserve the right to cut you off if they find out that you're using it for something nefarious.