How can the Arbitration clause be beneficial for the subcontractors?
Arbitration can be less expensive and less formal than litigation. It is also private, so there will not be a public record about the dispute between you and the general contractor. That being said, certain disputes cannot be resolved through arbitration. So even if you enter into a contract with an arbitrtation provision, any lien foreclosure would still be done through the court's system.
Further, the parties can waive the right to arbitrate. So if you or the GC bring claims in court, the parties can elect to stay in court rather than take them to arbitration.
You should contact an attorney to go over the specific arbitration provision at issue if you have more specific questions.