Whoops! I’m using SU 2020.
I would imagine a lot of the hobby modelers that still rely on Make 2017 are finding it harder to use the program, especially if they can’t use anything from the 3DW (at least not without the Eneroth load newer version add on). Still, that doesn’t seem to explain the increasing ratio of European/Asian to American/Canadian models available for download.
I don’t know if there’s an active Archive Project effort at preserving older models. Did the 3DWH have a wider selection 10 years ago? (I started using SU about 5-6 years ago.)