Partly correct, but for many years horn systems have included "phase plugs" or their equivalent to keep horns from "beaming" high frequencies. The high end horn systems I use for pro sound are designed to spread high frequencies over a large area, and they do that well, and the Klipsch Heresy IIIs I use in my home system easily have as good or better dispersion of high frequencies than the dynamic speakers I've owned over the years.