Yes, true, no SS classes for older models.
If you recall, SS classes for older vs newer models where different in the old rules.
SS classes for older models allowed minor changes, while the newer models had to be bare-bones stock.
Why -- because the number of bare-bone stock older models is pretty low.
It made sense in the old system to have a "modified" form of SS for old cars. In the new system, not so much, if you are going to allow changes; might as well be in the CC classes.

Not that I agree with all the point values... 