I agree with much of this, except the what technology question.
Cones are not all created equally. I'm sure all will agree. They weren't back then; they aren't now.
Technology has advanced with resulting improvements in materials (stiffer, lighter alloys, smaller magnets), and in manufacturing (eg, gold deposition processes, highly consistent thicknesses, and forming complex structures/shapes for rigidity). Compliance has improved. Someone more knowledgeable than I could cite more factors. Cones have improved. Design has improved. Whether these result in better sound depends on the particular models compared, and the ear, preferences and biases of the listener, among other factors - the usual suspects, like ancillary gear and room.
Cars have benefited from evolving tech, as has medicine and just about every human endeavor. Not surprising that audio has also. That doesn't at all mean that every new speaker sounds better than every vintage, obviously, nor vice versa. You get what you pay for (hopefully; research choices), but it was no more true this year than yesteryear.