>   Is there not a problem here: PostScript fonts may only come in one size,
 > which then is rescaled.
 >   But in correct typesetting, as in TeX fonts, the weights and proportions
 > actually change with the font size.
 >   So how does that work out here?

um, this is what i would call a canard. we have known this since the
first uses of PS fonts in TeX (I did my first book in LaTeX with Times
in 1986). its a fact of life that most PS fonts only come in 10 pt
size. Some have other sizes. Many Computer Modern fonts have a range
of sizes, some have more than others.

99% of the typesetting world gets by fine with the (technically
perhaps inferior) optical-scaling-plus-hints of Type1 fonts.

I suggest there are more productive things to worry about