Okay, think of it this way:

Say you're a widget maker. It costs you $500 to run all the machines you need to make 100 widgets. Next year, due to new widget requirements such as higher complexity or some other factor, the costs to make the same widgets has increased to $700. Your boss, instead of increasing your maintenance budget to $700 to cover the increased cost, only increases your budget to $550, which isn't enough to keep the machines running, and so you can only make, say... 75 widgets.

This happens year on year for over a decade, until the costs for running the machines are actually $2000, but your budget is only $1000, so you can only make 50 widgets. Yes, your budget has gone up every year, but not inline with costs, and as a result, you've actually received a 50% cut in your maintenance budget.