I'd imagine it's largely just due to a combination of inertia & ignorance (though the lack of clarity around display support is almost certainly a factor too).

I'd imagine it's largely just due to a combination of inertia & ignorance (though the lack of clarity around display support is almost certainly a factor too). Apple made a song & dance about it 7 years ago but releases of supporting displays since have been relatively low-key & I'm not aware of any online reference table tracking them - so my guess that support is broad is just that, a guess. I know Samsung & OnePlus phones have it & I assume Pixels (not checked), but laptop adoption could be much lower.