PE Preliminaries, page-7

Analysing the preliminaries is a necessary first stage to determine if further time and cost is warranted. In other words does the issue have substance. This stage helps the claimants avoid time waisting and cost overruns for no valid reason.Also the prelimaries could promote an early out of court settlement.
Anyone can commence arbitration with all sorts of wild claims that would clog up the system. This stage filters out those that appear to have a certain degree of legitimacy, based on the preliminary review of the TOR and the back up submissions.
Until the claimants can prove their case has just cause the claim is regarded with a certain degree of scepticism.
This is what I deduce following my attempts to research what is typical of the PE process.