Agreed. The cosmological model you use in your game says more about how spells like plane shift and teleport work than it does about the fundamental shape of reality. For all anyone knows, everything occurring beyond the Material Plane might be a shared hallucination approximating a multiverse mortal minds can't fully comprehend.
Well, the "Shadow Fringe" was part of the Plane of Shadow, which itself only became its own full plane (as opposed to a demiplane) in 3E, but was flat-out stated to cross cosmologies, so it could be said to be part of all of the presented options.
IIRC, 4e applied it to all of the settings. Even Eberron’s planes were organized into World Axis style groupings and the Shadowfell and Feywild were added to Dark Sun.
Back in our early days, we had a DM who had us land on the Earth plane exactly as portrayed in the 3e MotP. In that we landed in a pocket of air and had to wait until a summoned Xorn dig us somewhere that mattered.
To be fair, how many people have dealt with any plane that is not one of the Nine Hells or the Abyss, i.e. where one is going to encounter monsters to fight? I’m guessing very few have used the Good aligned planes.
There is one or two 4e adventure that travel to the elemental planes. In the Scales of War the PCs travel to the City of Brass in the elemental chaos/
