Concrete comparables
- BBS classifieds: countless hobbyist boards hosted buy/sell listings and private messages.
- Boston Computer Exchange (1982): a well-known BBS-based exchange for used computers.
- CompuServe Electronic Mall (1984): consumer shopping with brand merchants over dial-up.
- Minitel (circa 1982): a mass-market national platform offering commerce and services.
Conclusion
Because multiple, independent systems were already transacting online, a 1981 targeted outbound prototype for listings and exchanges was simply unprecedented. WPA was the small version of what soon became mainstream.