Addicted - That link/article was about oil finishes. That's why you didn't read anything about shellac/lacquer/etc. as those are solvent finishes. Varnish is also a solvent finish, but mixed with oils to produce various "marketed finishes" which is why the term varnish kept appearing.
Duke - I've never used pure tung oil, so no words of wisdom here. I am glad you were able to educate yourself with the products us consumers are purchasing. Like you said, the bottle of Formbys says tung oil, but that's not all that's in the bottle.
Gummi - For starters, I think I've helped blow this way out of proportion. There's really nothing "wrong" with any of the finishes that people posted/used. They must have worked and been happy with the results otherwise they would have posted a 'don't do this' comment. Take Duke for example - he's been really happy with his "tung oil finished" handles. But now he's aware that he's actually been using an oil/varnish mixture.
Oil & solvents like shellac & lacquer will make the grain pop. But, there's almost zero protection from those products. (on the exterior) Water & sun will wear out a pure oil or lacquered finish in no time flat. That's where the benefit of the mixed finishes (oil & varnish) comes in as you get a bit of both. And they dry a lot quicker than pure oil.
What do I think is the best practice? Keeping the grills under cover when not in use, dry as much as possible, clean, and some sort of finish that makes em' look good. What that finish is ----- no right answer. Personally, I'll probably use whatever I have on hand or what's available locally. An oil to make the grain pop and some sort of varnish to add durability. Might even be a deceptively sold product that's one-in-the-same as the linked article refers to.
My goal of making these posts wasn't to point out or say what everyone is doing is wrong. Just additional education for the stuff that's being sold so each one of us can make our own decisions.