Nearfield monitors are typically not prosound equivalents of high-end speakers. Natural sound is not necessarily a high priority for a nearfield monitor.
Main monitors on the other hand do place a high emphasis on sound quality. While it's true many studios use B&W or ATC speakers (the ATC midrange is short-horn loaded), TAD monitors are still in use in many studios. Genelecs use waveguides, which are a type of horn.
Horn loading of some type is more common than you may realize.
The coaxial units in speakers by Gradient, Tannoy, KEF, Pioneer (Model One, S-1EX and S-2EX), and others use the midbass driver's cone as a horn or waveguide for the tweeter. I'm presently learning more about this format, and have a coaxial-based speaker or two under development.
In many cases, the device or cabinet feature called a "waveguide" could just as well be called a "wide-pattern conical horn". Examples of such waveguide speakers include models by Amphion, Genelec, YGA, GedLee, SP Technology, Emerald Physics, and yours truly.
Finally, many modern horns are very low in coloration compared with earlier generation horns. Tractrix, hyperbolic, Le Cleac'h, oblate spherioid, bispherioidal, elliptical, quadratic, whatever the Oris is - these are some examples. Johnk, do you know what type of profile the Oris uses?
Once upon a time I administered a blind listening test involving a modern horn-type speaker. One of the listeners owned electrostats. In his notes, this listener commented that he suspected the speaker was an electrostat. I have demonstrated modern "waveguide" (wide-pattern conical horn) designs to literally hundreds of people, and not one has commented that he or she heard any cupped-hands or other horn-like colorations, and often I've specifically asked.
Duke