I agree it's better not to require an email if you really don't require one, but if you let users sign up without email, you don't need a library like this! So to me that's a better solution (don't require email), rather than using a library to detect throwaway emails which have legitimate uses for users as a form of spam mitigation.

But as a method of spam mitigation for websites it is terrible, because it excludes many real users who just don't trust the site enough yet and doesn't exclude real spammers who tend to use services like yahoomail. The problem I think is that sites assume a level of trust that just isn't there at the start of an interaction with a user.

It's similar to asking for real names - you can ask as a website, but you can't really impose that requirement in a meaningful way.