[8organicbits]

I suspect "fake" is the wrong word, maybe "very low reputation" is better. The parent post discusses avoiding giving unlimited free trials to people who just keep creating new accounts. You'll want to restrict that, especially if each trial costs a non-trivial amount of money. Efficiently detecting such abuse allows the company to offer generous free trials.

A side effect is that a small number of people who use disposable email addresses to manage the spam they receive will also be blocked (see other comments). A business looking at this issue may find it hard to prioritize, the group is small, and they can choose to use a non-disposable address if they want to continue.

[uallo]

The group of people that go through the hassle of signing up and setting up everything again to avoid paying is probably equally small. If the account setup is so frictionless that a lot of people do it again and again, you should work on adding benefits to loyal accounts instead of banning new users.

[8organicbits]

You can actually check how many users it impacts by watching how the bounce rate changes after a user with a disposable email address is told their address isn't accepted. Adjust course based on your metrics.