There are a number of flowers that just do not lend themselves to either a steam (e.o.) or other solvent-type extraction. For various technical reasons they are too fragile or they rot or so on. So Lily of the Valley is one. It is primarily synthetic, though nicer ones often have "compounded" formulas that probably include naturals like ylang, jasmine, and other florals.
Sadly, a lot of other favorites are synthetic-only, like wisteria.
That is not to say that I see them unilaterally as "bad" since many of these partially synthetic florals smell really incredible.