>Suppose you need to track the changes done some days ago, what do you do? restore the backup ov every day and compare? Could be very time costly. With Source Control (any tool, even old SourceSafe is better than no Source Control!) you just select a point in time and Diff, then go back to previous changeset and Diff...

And supposing you trained your developers (and yourself) to leave a meaningful comment when checking in, a brief description of what was done and where, this can be even faster.