One might expect that over time economic forecasters should converge in methodologies, and thus in forecasts, as the competitive market for forecasters creates a natural selection that weeds out unsuccessful strategies and pushes forecasters towards the most successful strategy.
However there is still a wide divergence in economic forecasts, which begs the question what part of that natural selection is failing? One could argue that there is no “most successful” strategy, and that the best model shifts in random in unpredictable ways.
But I don't think actual models change fast enough to account for differences in forecasts. You could also argue that some forecasting strategies are not public knowledge as forecasters keep them secret. This is probably true to some extent, but I doubt if everyone had perfectly transparent models we would observe this convergence.
A third, and I believe most important, explanation is the failure of the assumption that the competitive market for forecasters creates incentives to have the most accurate forecasts possible.
Source: Seeking Alpha