When I get in front of a classroom and my tech isn't working, I call a number and they dispatch campus IT immediately to my location to fix it within 5 minutes. This kind of rapid response and support isn't possible for a department to fund, especially if it's a department like History.
Face it - students have higher expectations now, professors also have higher expectations. This requires administrative staff to run. Back in the day school budgets were lower, but even when I went to college in 2005 they didn't have campus-wide wifi in every classroom. We had one professor who taught with powerpoint. Today, every student has a laptop in class.
Maintaining a modern campus takes a big IT department and centralizing it is the least wasteful way to do things.