If history tells us anything, it's that the meaning and use of words is fluid, and that they change.
Gay for example used to mean happy and carefree, but now has a commonly much different meaning for many. Bad can mean different things to different groups of people ...... and I dare say if I think hard enough I can come up with a few more examples.
Solid State to me, is just a term used to differentiate devises that have no "obvious" moving parts, from those devices that do. Is it a marketing term ...... sure it is, but it's a term that most people are familiar with, and I would imagine that most do not believe it is a statement of actual fact, it just acts as a useful descriptor.
As far as I'm concerned, the purpose of this forum is to help people with their problems, and along the way to educate them a little, and whilst solid state may not strictly be an accurate descriptor, then it is at least one they're familiar with and will understand when it is used.