As somebody on the receiving end of IT "help", I'll tell you why I get annoyed.
I have a job to do. At home, the process is simple. I turn on the computer, and it just works. However, on the job, it feels like the IT department is trying to make my life as difficult as possible, while admittedly streamlining their own work. Sometimes I make requests that would save me hours a day, and the IT department complains because it will slightly increase their own workload. As for certain simple programs, and it takes them weeks to install those programs, costing me hundreds of hours in productivity a year.
I get that IT has a job to do, but it feels like IT often forgets that I have a job to do as well, and that at the end of the day their role is to facilitate my ability to do my job.
As the parent said, IT often sets things up in a way that is best for IT, not necessarily for the other employees... and that is objectively not the role of IT at all. As one of those employees, I am aware that IT is making their life easy at the expense of my productivity, and it really really really annoys me.