Sorry, but it would never work.
A number of new sellers have a mentality that experienced sellers are somehow unworthy of the amount of orders they receive, and that they could become just as successful, if not more-so, if they were just given a fair chance.
Everyone once started as a new seller, and being a new seller with no track record is indeed a difficult state. The thing is, success begets further success, and failure begets further failure. Momentum as a seller is a very real thing, and having successful orders with happy customers makes getting future orders ever-so-slightly easier.
Unfortunately, the opposite is also true. Disgruntled customers, low reviews, cancelled orders, and complaints made to CS can destroy positive momentum very easily, and can send a seller on a downward spiral to oblivion. Trying to recover from such negative momentum is very hard to do, and it’s best to simply never enter such a state of affairs.
A “decentralized allocation system” to give equal promotion and visibility to any and every gig would fly against the face of a merit based system. If I were a buyer, I WOULDN’T want to have my search results scattered with poorly rated sellers with terrible response and completion rates.
An order outsourcing program would be an absolute nightmare. A seller becomes busy in the first place by the quality of their service and deliveries. If they outsourced orders to someone else, they jeopardize their own reputation and likely will receive work completed to a different standard than if they had performed it themselves.
The fact of the matter is, there is a tiny, top echelon of sellers who receive a substantial amount of orders, a much larger group of experienced, established sellers beneath them who are eagerly trying to join the top spot, and a massive number of sellers beneath them with little or no orders and reviews who are trying to carve out a presence on the platform.
Success is never guaranteed, and trying to make the platform more “fair” will still result in some sellers being successful, and many others not. No matter what, Fiverr can’t force buyers to make a purchase, or dictate to whom they should purchase from.