Non-technical people have a very strong tendency to treat their co-workers in I.T. as their personal tech support, and managers outside of I.T. don't understand why you can't just make the developer/sysadmin/network engineer/dba/whatever do all the BS helpdesk work at the same time.
Being an uncommunicative jerk is considered a more forgivable trait than actually pushing back on the work put on your plate.
In my first job ever, I spent about six months helping anyone who came by my desk for help. As it would turn out, my manager completely hated the fact that I did that because it looked like he couldn't keep me at 100% utilization.
He was much happier after I grew a neckbeard, long hair and turned into someone who'd bite the head off any QE who came by my desk with random questions.
More than a decade later, way out in open-source, I have gone back to being nicer & calmer - because nobody knows your hairstyle on the internet.
It's like that whole trope of "don't fix the copier, then everyone will constantly come to you to fix the copier".