Main reason are costs for mass production, and nuances of technology, that electronic components usually made in very huge batches, then distributed to distribution network and lie on storage up to tens years.
So manufacturers made series of agreements, like "in 2020-2025 make e3; in 2025-2030 make e12".
Expensive high precision parts, are not in this scheme, they allocated by direct requests, like Toshiba manufacture high-end transistors, and order for them high-end resistors with some exact value.
So manufacturers made series of agreements, like "in 2020-2025 make e3; in 2025-2030 make e12".