"All of this applies to meetup.com as well as eventbrite.com
The deeper problem of using eventbrite to register people for an event is that it collects data about them and gives it to a company (with big brother reading over its shoulder).
If you want to register attendees for an event of any kind -- whether it is for business, for pleasure, for education, or whatever, please do it the ethical way: don't make them run any nonfree software, and don't make them send personal data (not even to you). That's how the #FSF
does it. We don't insist on getting a person's real name. When we charge for attendance, we accept payment in cash at the door.
When you invite specific people to a private party, perhaps you know exactly who is coming because each one is your friend. It is natural for you to know that — just don't dox your friends to a company such as eventbrite! "