The absolute default standard used to be a machine with just a sanding belt in it. Just about every shop on the planet has or had one at some point. Then people started to figure out that the sanding belt made the parts sharp as a razor and occasionally threw a part across the room just out of spite. You needed to run a file or another tool around the edge or be sure to put on your gloves.
The next step was people figured out that if you put some kind of brush behind the belt it would reduce how sharp the part was when it was done. And it would occasionally throw a part across the room out of spite. The adventure started when everyone started trying to figure out what kind of brush worked best for the task. This started the process that left us with seemingly hundreds of brush types in the wild.
Some of the many brushes work well to produce a finish but stink at rounding over the edge. Then some could round the edge but the finish was not good. Some became a jack of all trades and a master of none. With so many designs and brush types what do you do?
Tools in finishing are like ingredients in a cooking recipe. Some work well with others and some just do not get along at all. Just like you would not want a vinegar sauce on your chocolate cake some finishing tools just don't work together. This is where experience will come in as it takes a lot of testing and A wide part variety to know what tools do what and in what combination. I will give a few points to convey what I mean.
Sanding belt at the out feed of a machine. This has become more common it seems with many offering it as a solution. The idea is the belt as the last step puts down a straight finish as the part exits the machine. There are some issues here that make this less than desirable. We know that a regular sanding belt creates a sharp edge, we learned that in step one of finishing machines years ago. So if you put a sanding belt at the out feed of the machine you are just making it sharp again. "Well smart guy I use a scotch brite belt" Have you seen how much those belts cost now? Or how long they last for that matter. Then you have to remember that belts have to track back and forth when they run so you get the zig zag from that tracking in the finish. Well you could speed up the feed belt to help reduce the zig zag effect in the finish. Problem is now the part is going through the machine too fast for any brush to have time to work. So you end up with worse performance from any brushes and a part with zig zag to the finish and possibly a sharp edge.
Mop style brushes. We have all seen them and they run under many different names but they look like a string mop made of sandpaper. The thing that jumps out at most people is they touch the feed belt. Well that is true that sandpaper is rubbing against the expensive and hard to replace feed belt. There is no support behind the sandpaper so its just slapping the part and sliding over the surface. Any person who has ever sanded anything by hand can see the issue here. Even if you try and get dry mac-n-cheese out of a cooking pot you know that you need some pressure. You have to scrub at the pot to get it clean and slapping it with a string mop wont be your first plan. Are these brushes a scam? Not at all as they have an application where they could be the best answer. If you have an up form of some type they would be one of the few brushes that would work. With laser splatter they would in no way be my first choice as you just cant get the pressure for them to work the surface.
There are brush stations available that can break the edge while removing the bur. That means you would not need the sanding belt as a first step. You also remove many of the part size limitations by removing the belt as well. A sanding belt is the main way a machine can throw a part out of spite and you may not even need it. Removing the sanding belt is a very viable option for many people but not all. If you need a grain finish you need a belt plain and simple. If you are needing coating prep a sanding belt can hurt more than help. Belts can leave a deep scratch that will show through the coating, if you are looking for a smooth finish that is no good. Random shallow scratches from a brush tend to make a good key for adhesion with the added plus of rounded edges to avoid thin coatings.
So do you need a sanding belt? If you need a grain finish then yes you do, but having it at the out feed is not the best plan. If you just need to remove the bur or round the edges then you may not need the belt. It lets you get a smaller lower cost machine that produces what you need. It will depend on your material and how you are cutting it as you would expect. Flame cut cold rolled steel is going to need a belt to cut the dross for sure. But if you laser cut aluminum there is a strong chance you don't need the sanding belt. Dropping the belt lets you save money on the machine as well as not needing to buy the expensive wide sanding belts. Its not an option for every shop but it is an option for many.