In 2003, Thomas Carbonneau wrote that "freedom of contract . . . Is at the very core of how the law regulates arbitration," and he referred to this as "Contract's Empire." I think Carbonneau is right and that, if anything, arbitration law has moved even further since then in the direction of contract.
Caroline Myrdek, Sixth Circuit Deferential Treatment of Notice in Employment Arbitration Agreements: A Comment on Tillman v. Macy's Inc., 8 Y.B. Arb. & Mediation 122 (2016).