Text is rendering blurry in the thing I'm building. It used to look nice and crisp, but now its as though it's all nudged half a pixel off the grid. It looks terrible. And I don't remember having touched the text rendering stuff or the vector code recently. wtf?
So I pull up the change log for the project and it gives me a giant list of everything that has ever been done on it back to version one where it was nothing but "test.html" moving a yellow box around the screen in time to an audio track. I grab a version from a few weeks back, 50 checkins ago, and click "update to this version". Reload the project in a new tab and sure enough: beautiful crisp text. Tab over to the current version: blurry blurriness.
So it's on. Jump forward to yesterday: still bad. 2 weeks ago: good. 1 week ago: bad, and so on. Until I'm looking at one checkin that definitely contains change that broke this. As luck would have it, it was a big one, so I get to try individually updating each file in turn. And since the culprit is nowhere near touching either text rendering or vector stuff, I get to go line by line on it until in disbelief I find the single "if" statement that's been flipped to a configuration that allows opacity animations to occasionally get left at 0.9997 instead of locking them at 1.0.
And we're fixed. In ten minutes.
Now I can honestly say that I don't think I would have found the cause of this bug without version control. All the places I would have thought to look were innocent, and the most innocuous thing in the world turned out to be the culprit. With nothing but tarballs and hand-renamed folders I would have been completely screwed. Not just more time to fix this, but several orders of magnitude more time. And most likely we would have simply resigned ourselves to ship with blurry text and kept an issue in the tracker about it for years.
Now, in case you missed it, this happened to me three days ago. It's not some isolated instance I heard about once. Version Control saves you like this on a daily basis.
If you see a software company that's currently in business and shipping software, I'd say you can use that as empirical evidence of the value of version control.