I don't know what kind of breakage was the parent talking about.

My experience is that as the car gets older it is common for the vents to lose the capability to stay pointed where I place them. As in: you point them where you want and they flip back all the way to one side as soon as you let go.

(Hot climate here, with several months of "a/c set to max during the whole trip" per year)

I’ve been in many cars where they don’t stay pointed and where the moving mechanism plastic broke off from where it’s connected so it doesn’t move the vent fins at all.

Plastic in the 1990s was more brittle than today. Even back then, my 10-15 year old Ford had issues with the vents not easily moving, then breaking from force.

More modern cars of decent build do not have this issue.