Why not horns?

Mapman, those horn loaded German Physiks are at the lower end of the line for German Physiks. Their top tier products don't use horns. As for the reviewer, I have no idea who he is, but he's entitled to his opinion.

Macrojack, that link seems have started with regard to a driver, not horns in particular, though it did seem to drift there, at least in part to you.
A few audiophiles are unaware of the performance limitations locked up in this technology.

"he's entitled to his opinion"

Yes, opinions are opinions but for any somewhat credible source to indicate that $1000 low end speakers from one line can match $21000 lower end models from another and higher end models selling for only a few thousand more outperform the $21000 speakers using a similar technology in every way is an eye opener that at least has to make one take notice.

Mapman, what makes it a "credible source"?

He apparently has ears and has listened to a lot of stuff.

The same credentials as most of us I would say.