Often when you have to qualify something (intellectual property instead of just property), it's because it's used as a metaphor instead of a subcategory. Intellectual property is a form of property as much as political science is a form of science.

You can metaphorically say it's theft, but it doesn't manifest as theft of actual property.

For example: many people (myself included) have downloaded the $1.000.000 torrent (a list of files whose value amounts to a million dollars). I found nothing of use in it so I just deleted it. Did I cause a million dollars in damages? Was the damage restored when I deleted it?

If you consider the same for actual property there's no question about it. Stealing a Bugatti does cause millions to be lost, and destroying it makes it irrecoverable.