This post starts with the implicit assumption that the normal structure for a meetup is a talk. Is it?

I don't go to many meetups, but by far the best are the ones structured for peer discussion, not lecturing. Extreme Tuesday Club has been doing this for decades:

https://exubero.com/2018/12/16/joes-farewell-to-the-extreme-...

The London Software Craftsmanship Community round table meetings are similar:

https://www.codurance.com/publications/2011/08/20/one-year-o...

How common is it to have structures like that? Have i just been lucky?

The specific office hours format is different to either of these, but it's a similar flavour. I'd like to try it (which means i should propose it for XTC).