Truly, a universal size, works on almost all brass, only does one thing, knocks out the old primer so you can replace it with a new one.
At one time, handloaders just used the decapping pin built into most sizing tools, you can still do that today if you want. Decapping prior to cleaning is by far the most common current procedure used by most handloaders today.
Decapping your brass, then cleaning it allows for a much better case inspection which is a very important part of the loading procedure at every given point. It also keeps your precious sizing dies clean which is also very important.