You are confused because you are thinking either/or. Using compound on the compression nut is a "belt and suspenders" method. There is nothing WRONG with using compound, but there is little, if any, benefit either. I just don't see any reason to waste my time disassembling the valve and then putting it together again.
It just occurred to me by looking at my pic that you might think my comparison is of a threaded Brasscraft and a dahl with a 1/2" compression nut because it looks too big . To clarify, it is a 1/2" female pipe thread for nipples and adapters. It is more than twice the material that the Brasscraft is made from.
Put the pipe dope on the ferrule, a little on the threads can't hurt. the dope on the ferrule reduces the friction, making it tighten up easier. You want the ferrule to compress onto the pipe without spinning. Installing without pipe dope is ok as long as you don't have to reposition the angle of the valve later and youget it tight enough. If you have to adjust the angle of the valve later and there's no dope on it then it will leak.
The problem with Socialism is, you eventually run out of everybody's money! Margaret Thatcher, I believe said this. Also, I think Canada is giving up on their health care system because it does not work. The Health care in Canada was far from free.
when the automatic headlights on my Dodge stopped turning off when it was light, I took it to the garage to have it fixed. Their solution was to say, "Now you have daytime running lights, and since it was made in Canada, where they are required, that is probably how they were supposed to work in the first place".