I don't think my question is rather pointless, that's kinda rude of you. You seemed to have jumped to a conclusion where I'm trying to upgrade on Qantas using Emirates miles/points, which I don't know how you got there.

I'm simply asking about airlines where it might be technically possible to go from eco to bus based on the (possibly flawed) assumption that you can only go up one class as per my experience with BA.

TBH, asked and answered at this point, I'll examine more than just 1 or 2 airlines next time I'm booking to see what's possible at the time.

Sorry, shouldn't have said it was pointless.

I just mean that knowing all the airlines X that only offer 3 cabin classes (or even 2) isn't much use if the reason for asking is to be able to upgrade with miles/points from airline Y and Z if they don't allow you to upgrade flights on X. It seems like you're trying to approach this the wrong way around.

You are best off understanding the program rules that you have miles/points/avios with or can transfer to. Some will allow you to upgrade from economy to business even if there is a premium economy cabin.

Also many airlines only offer 2 class (economy/business without a first class), then some have 3 class but economy/premium economy/business.

easier list is how many have y+

I don't think there's many anymore that are F/J/E...most of those planes are either J/E+/E or F/J/E+/E since E+ doesn't really require a cabin divider per se but they can squeeze some more money out of it.

What airlines offer true premium economy and don't use a cabin divider?

None that I know of, but we weren't necessarily talking TRUE econ plus as I read it