I have come across the same suggestion twice in a short span of time. Last week, I was on an expo and I learnt that the milling process should be completed using different tools; then I went to a local artisan's shop and he was talking about how using different drill bits and heads made his work so easy and flow seamlessly. Now, I did not want to look like a tool/the fake apprentice by asking something as 'obvious' as that.
I have a nagging suspicion that it may be used for smoothing rough edges on the finished work. AMIRITE?
Note also that there is the process of deburring. This is mostly applicable when you are making some parts/tools using a CNC machine. De burring is done after the job is finished, and takes quite some manual labor. However, there are other tools that are used for the same job - but they have only been recently taken up.