I believe it's supposed to etch / frost the metal.
Other controversial bore cleaning methods for removing carbon is using CLR.
I have not and don't think I will. Lots of division on that one.
...shoot it until it does shoot like it used to,
Did it used to shoot 1/4 MOA or MOD (minute of deer)?

Yeah that's one of those non-quantitative statement gun people to like use, like "shoots better than I do."
Gun stuff, shooting, reloading, you have to take all the info you get from the perspective of the person giving it for it to have any value. And that's tough to do most of the time. Everyone has different standards, but also tend to dismiss anyone who's standards are above or below theirs. A PRS guy for example may scoff at what a regular hunter does and the accuracy level he accepts. But will also scoff at the accuracy level a benchrest shooter will accept and write it off as silly and "unrealistic". You kind of see it all all levels and all disciplines. "What these people on this side of me are doing is dumb. What the people on the other side of me are doing is just silly. What I do is right."
Ruger single actions, a common modification to improve the action and trigger is to put in a reduced power main spring. And for years I would preach to people not to, that it slowed down lock time and was detrimental to accuracy. And so many people would argue with me that it wasn't true and they had no issues with them. The delicate part was, there was no way for me to argue without sounding like an @-hole. Because the blunt truth was "if you can't tell any difference, that just means you can't shoot well enough to notice the difference." That wasn't a huge slight, fact is most people can't (I sure can't anymore, those days are gone). But I had to learn a way to share the information in a more technical way, to not hurt feelings, not make it personal, not challenge or question anyone's abilities, so they wouldn't naturally turn defensive and just dismiss the information.