Companies I’ve worked for use “trade” distributors like Arrow, Avnet and a bunch of others most people have never heard of. Larger companies go further up the distribution chain up to the manufacturer themselves.
The design engineers select parts and specify alternatives, but it is up to the Purchasing department which variant they buy, and who from. They do not use the CAD tool that the designers use. In fact there is a completely separate software package that Operations use for ERP that integrates purchasing, stock control, production, sales orders etc such as SAP.
Component data is kept in a separate database, which has additional info relevant to designers, but is linked by “house” part number to the main ERP database, and kept in sync. Data from that database is then extracted to create libraries for our CAD tools (schematic, layout, MCAD). The CAD tools used by the engineers are just a cog in a big machine.
Obviously we have an IT department and other “programmer/engineers” who maintain the databases and bespoke scripts.
All the above can and is implemented outside the CAD tool. Therefore in principle, KiCad already has the features needed. All it needs on the user side is some method of generating libraries for KiCad, which is dependent on the local requirements which really only the user can implement. It’s not practical for KiCad to contain interfaces to every type of ERP tool and every electronics distributor.
I think what people are really looking for is a free ERP tool, that can be adapted for use with KiCad.