What's the ROI of Everything Other Than Social Media?

The first Buzz2010 event is over, but there are still two more to go! On July 20 I'll be going to Managing Risk and on August 18 I'll be going to Social Media ROI. Woo hoo!

As if I weren't already psyched about both of those, this awesome slideshare by Olivier Blanchard is a must-watch and his session in August will, I'm sure, be equally don't-miss.

Here's what I want to know, though: with all this talk about the ROI of social media, why is it that nobody ever seems to stop to look at the ROI of anything else? Yes, social media is new and therefore under the microscope--but isn't there some business thing that says the ROI of every business activity should be regularly scrutinized? It seems to me that once something becomes established as "ROI positive" or whatever people are trying to prove that social media is, it becomes grandfathered in and nobody ever questions it.

So instead of questioning the ROI of social media, I personally wonder if others have to go through such hoops to justify their jobs. Like PR, for instance. What's the ROI on that? How about accounting? Payroll? IT? Do organizations regularly take a microscope to those positions to decide if they're still relevant, still worth the same salary, still worthy of X number of staff positions?

If not, why not?