GitHub's terms: A2 – You must be a human (help.github.com)

Should this become something usual in the terms of services ? Maybe it's something usual already

On https://developer.github.com/guides/managing-deploy-keys/#ma...

Tip: Our terms of service state:

    Accounts registered by "bots" or other automated methods are not permitted.

This means that you cannot automate the creation of accounts. But if you want to create a single machine user for automating tasks such as deploy scripts in your project or organization, that is totally cool.