> I would hope that isn't true, an economy would function horribly if we only cared about the price change percentage and didn't care why it happened.

That isn't what I said.

The causes of inflation to matter, but we generally only care about them because they cause inflation. We don't tend to care nearly as much about the causes in and of themselves.

Thus as the argument about how much inflation there should be progressed, it is perfectly natural that the term came to refer to the part of the debate we actually care (how fast prices rise) about rather than factor that can sometimes cause it.