Where a single, basic kit will hit the market - say, a C8 Corvette, or a pickup of some type, and rather than cutting several different inserts at great expense, the modeler simply orders up the remaining bits to complete the project.
The variations are slight, but the builders who seek them are the ones willing to pay the most to get them. The value added is great, and the cost to distribute is negligible.
I see this as a much bigger deal for the IPMS and Sci-Fi universes - where even minute variations are celebrated and examined in painful detail.
It all reminds me of the 'resin revolution' - where within a few years, modelers who loved the subjects but were unlikely to possess the scratch building techniques could finally get parts and kits that were either unobtainable, or too niche for majors.
Once the technology was sorted and a few leaders emerged (Don, others) then it was a widely accepted practice and the "mavens" of the hobby memorized the catalogs, offered new subjects and ultimately saved the hobby.