First of all, because anxiety and depression are well known to manifest with physical symptoms. Which is why if you present with physical symptoms, anxiety and depression are diagnoses of exclusion, coming long after everything else has been exhausted. Notably, I didn't say they're /imaginary/ - just psychogenic. Anxiety is well known for significantly reducing the threshold for attention to stimulus: someone having an anxiety attack can feel things without somatic prompt, or they can feel something horrible with an underlying somatic prompt that, if they weren't having an anxiety attack, they'd never have even noticed. Generally people don't get brushed off as having mental disease. Although that's the popular narrative, again, (1) it's usually the last dx, and (2) even in these people's narratives, they go from physician to physician. Doctor after doctor looks at them and detects nothing.

This doesn't mean nothing is there, of course, but mystery illness is rare and anxiety is very common. It would be bad medicine to overlook the prevalent condition that explains your symptoms.

Second, post-surgical anxiety is quite common for a variety of conditions. I actually addressed it at the end of the post I suspect you didn't read. You presume this is somehow unique to turbinate reduction; that is an untrue assumption.