The last good good horn speakers I've heard, were Aries Cerat horns. They still exhibited "horn sound" to my ears, when played loudly. As did the last two Avantegarde models I've listened to (the Duo and Trio) and the Classic Audio horns when I heard them.Cupped hands effect is simply non existing with a quality horn speaker. We need to understand that price, purchased reviews (yes, that's often what they are), and rumours say very little about the quality for a speaker.
Some of the long existing and known brands have very poor tehcnicial implementations. Typical charactersticis like strong beaming, non uniform directivity, non optimal crossover-overs with serious vertical phase and lobing issues, coloration from material/lack of rigiditiy, passive crossover with no time alignment between drivers and uneven response, diffraction issues with horns placed in front of the other, and low driver quality are often the norm.
One has to look for quality technical implementations and good measurements.
The vast majority of the time, cupped hands and shouting aren't a thing. But sometimes, depending on what you're listening to, they are. It's rare, but it's there.