You're probably right about the swager, altho I've dealt with a bunch of cases that had been swaged and priming was very difficult. I still cut a small "starter" taper on those.
With the staked primer pockets I mention, those little hand tools that limit the cut will never get past the "Squaring" of the primer pocket that the staking induces. You cut a little way into those, and you can see that the pocket is deformed by the staking. Swaging would probably reform that enough. I bought a hand tool, made by Lyman (whom I had always trusted) that claimed to be a primer pocket deburring tool. Egads! You can't get through 100 pieces of brass with that GARBAGE before you decide that there has got to be a better way.
I vehemently stand by the time tested deburring tool because I came up in a time when just about anything a man may endeavor to do could put him at risk of over doing it. Try flame cutting titanium, or building high pressure propulsion piping systems. You use the right tool for the job. Use it wrong, and you might set the county on fire. Do it right, and the biggest war ships on earth can go 80+ mph. There is a huge measure of discernment, skill, and mechanical aptitude involved in reloading. A man who has been seeing his method work for decades will not be told otherwise. He'll try to pass his methods on to the kids who are next to try.