It's not about being a prima Donna. It's about business value. Too many meetings over the years should either be better planned, not taken place at all or could have been an email/chat message.

Business value first

You’re both in agreement that most meetings are unnecessary and that it would be better if meetings had a set agenda.

But the other poster was saying it’s prima donna behavior to skip a meeting without asking the organizer if they can add an agenda first.

Meetings with an agenda are generally better, but that doesn't mean meetings without one can't have any business value. If you skip it, you make sure you at least don't contribute to anything decided in it.