It sounds like a problem the IT department should solve. No?

It is, but solving that problem would entail re-training staff, reduce "productivity", and moreover, cost money... Many companies have cut their IT provision below what is needed to simply stand still.

IT is a cost to their business, not a revenue source. They don't consider the counter-factual of "well, what if we didn't use IT and computers and the internet" when valuing what IT is bringing to their business. If they did, they'd perhaps be willing to spend more.

MBAs don't like spending money on something that doesn't yield them more sales though...

MBAs don't like wasting money. If bad IT costs them money or sales they care. If they can reduce the costs without losing that money they will. However they don't know how to solve this optimization problem and are learning the hard way when they get it wrong.

I think part of the issue is also that the negative impact of getting IT wrong is delayed, and often lands after your middle managers have moved on to other organisations, thus don't see the impact of cutting costs repeatedly.

Since there's no visible problem (nothing catches fire) the day, week or month after cutting spend on IT, it's an unnecessary expense in the eyes of beancounters.