Many failed online shopping malls chose to showcase services that have a low transaction frequency, which prevented any real growth in the market.
For example, Beepi
was a peer-to-peer marketplace for buying, selling, and leasing used cars. The reason why multi vendor marketplace failed was the lack of transactions that occurred.
While it was possible to find a person who is selling a used car, finding two people who would like to implement a selling/buying deal with the same car is much harder, and, as a result, it's almost impossible to scale such a concept. A lot of cars stay unsold, which means that the multi vendor platform remains stagnant.
Another pitfall with transactions frequency is services where customers prefer a monogamous relationship—like with babysitters, for example. It is easy to see that users would prefer not to hire a new babysitter constantly, as there are issues with trust and safety when it comes to one's own family.
Thus, it's better to run a multi vendor mall for a service with high purchase frequency and regular usage.
Uber, for example, matches both conditions. The demand and transaction frequency is constant since people require and ride taxis on a daily basis.
Consumers then rely on the web marketplace as an everyday utility and continue using the same service as long as they're satisfied.