I'm told this releases the impurities, i.e scum, so you don't have to skim while simmering.
This sounds counterproductive. Making stock means that you let the boiling water leach nutrients, flavors, and other stuff from the bones. Then you remove the solid parts (bones, scum) and are left with the gelatine and flavors dissolved in the water.
Now, if you preboil the bones and throw away the water, you throw away all the flavor which has been leached in this boil. Sure, some flavor will remain in the bones for prolonged boiling, but it will be less, and it won't be the same flavor (some tastes will cook out sooner than others). In short, the process which creates scum is the same which creates stock; you can't have one without the other.
In your home kitchen, you can mostly live with cloudy stock if you don't feel like skimming. Clear stock is more desirable, but you can keep that for special occasions. And exactly these occasions are the one when you want the most flavor, so don't compromise by preboiling.
If you wish to remove surface impurities and coagulate the surface proteins* for a clearer stock, then you might choose to do that. Keep in mind you might be sacrificing taste over aesthetics. It will most likely not totally prevent scum from emerging anyway.
You could try to make a stock without skimming and see what you think (related question - Why skim “scum” from the surface of a simmering stock?). I bet it will still taste great.
*If you are making a brown stock by roasting the bones, you have already coagulated the surface proteins.
Pre-boiling can create a lighter-colored stock, especially with beef or pig bones. See: http://www.seriouseats.com/2012/02/how-to-make-tonkotsu-ramen-broth-at-home-recipe.html. This didn't create a clear stock (both versions were opaque), but boiling the bones changed the color of the stock from brown to milky.
I doubt that you'd get as much benefit from doing this with chicken bones, and I'm quite happy using brownish chicken stock for cooking at home. If you're trying to make something as clear as consommé, you'll need to do more than just rinse the bones off.
I make stock from all animal bones (chicken, beef, pork, haven't tried fish but I just may). Every time icook anything with bones, i make sure I get enough bones to boil for stock. Therfore each stock has all the flavor from how I prepared the mask that time. I never pre boil, you want all those flavors to not be cooked off. If you want a clearer stock, after you've drained the broth from the bones (I boil for about 5 hours on a very low boil, but that's just so I know I get the marrow too) then put some egg shells in the water for another hour or so, and the egg shells will attract the grime and leave the stock looking clearer. Once done boiling, then strain the stock from the egg shells, cool, and I put the broth in ice cube trays and freeze it, then put the cubes in a zip lock in the freezer so I can choose how much I want each time. I also use some stock to make BBQ sauces -primarily pork and beef. It's yummy.