BF wrote:

2. Not disputing the definition of a vector, which indeed has no
thickness. But, every cad system that I've used, and there are quite
a few, are capable of drawing lines with thickness and the thickness
does scale.

Certainly, you can always draw or convert to a polyline and assign thickness
but this wasn't meant to be a discussion about CAD.
If vector chart systems use something similar, which would increase the data
storage file sizes significantly, then the OP must be talking about
something different than what I demonstrated.

--
Roger Long