Theatre professor here! My professional productions are expected to be my entire body of research toward tenure.

The author is already tenured in France and is mostly arguing that they need to "publish or perish" to get their PhD students to graduate. My experience in academic computer science in France (though not in the author's specific subfield) is that many many very good PhD students graduate with one or two conference papers published, and nobody minds, and they go on to good positions after that. I agree with the grandparent that the author might be overstating the problem a bit, in their very specific context. In other places, sure, students have some dumb quota to fulfill. But putting this front and center as the argument for leaving a tenured job in France... doesn't agree with what I've seen.

It depends on the field, but yes. Many optics researchers really only do presentations and they 'count' as paper publications. The pressure is still intense though.

Some areas focus on conference publications rather than journal publications—in optics is there no conference publication, just the presentation?

Oh man, yes, you are correct. My brain was somewhere else. My bad.