They're NMDA antagonists primarily, the same primary mechanism as ketamine. They're dissociatives
From Wikipedia's definition: "A hallucinogen is a psychoactive agent that often or ordinarily causes hallucinations, perceptual anomalies, and other substantial subjective changes in thought, emotion, and consciousness that are not typically experienced to such degrees with other drug classifications."
The traditional dissociatives definitely would classify as changing your thoughts and consciousness.
This is extremely broad, in that case cigarettes are hallucinogens. Nicotine is a psychoactive substance, it absolutely alters though patterns and consciousness.
>often or ordinarily causes hallucinations, perceptual anomalies, and other substantial subjective changes in thought, emotion, and consciousness that are not typically experienced to such degrees with other drug classifications
I think you left out an important part of the stated definition, this also says "and" rather than "or". I think that "dissociative" is a more accurate classification the the compounds' primary effects seen at the majority of doses.
I mention in another comment in this thread why I think it is a poor classification, please refer to that message for my argument.
Calling something a hallucinogen, while true a portion of the time, gives people who are unfamiliar the impression that it produces hallucinations most of the time, which it does not.
I would generally agree that calling it (or an analogue of it with a similar profile) a (bespoke) hallucinagen in an article isn't very accurate though. I was fascinated by the hallucinations that ketamine induced in me, and sought them out, but they were actually quite unreliable to attain and seemed to require a very specific dose range and set/setting.