Because a CD is obviously an analog medium.
Because, when you put two CPUs on a single die of silicon, it magically becomes one "CPU" with two "cores".
Well, "dual core" is a nice and compact way of stating the idea, particularly as it doesn't clash with any other meaning. That said, what kind of a person names a dual core chip "Core Duo"? Someone from Microsoft?-) Then again, better let marketing name a nice product in a silly way (I did buy a Core Duo after all), than let them design a CPU, like what happened with Pentium 4.
What are electrons, photons and magnetic fields, if not physical entities? Mere figments of your imagination?
As used with computers, this does have some legitimate uses, but it is often superfluous and even misleading.
When I think of defining this word outside IT, I think of supporting a sports team. If you support a team, you're a fan. You're biased to act in favour of the team, to help them out. On the other hand, you're not solely responsible for their success. A bunch of fans cannot save a team that's inherently incompetent, but they can help a good team perform a little better.
In the same way, support in IT does not guarantee full success. More importantly IMHO, lack of support does not mean that something doesn't work. There's lots of hardware that doesn't support Linux, but Linux nevertheless runs on it, often better than the officially supported operating systems.
When it comes to computers, I'm interested in whether they work, not whether they have fans.
Therefore, by the useful kind of support I understand something like customer service. Support means I can complain if I have problems, and I get help; it's like a warranty. If there's no support, I'll just try and solve it myself, or with the help of others.