Instead of dwelling any further on the majority's outcome-driven "reasoning," I will quote this passage from Justice Ginsburg's dissenting opinion:
I write separately to emphasize once again how treacherously the Court has strayed from the principle that "arbitration is a matter of consent, not coercion." Stolt-Nielsen S. A. v. AnimalFeeds Int'l Corp., 559 U.S. 662, 681 (2010) (internal quotation marks omitted).
Congress enacted the Federal Arbitration Act (FAA) in 1925 "to enable merchants of roughly equal bargaining power to enter into binding agreements to arbitrate commercial disputes." Epic Systems Corp. v. Lewis, 584 U.S. ___, ___ (2018) (GINSBURG, J., dissenting) (slip op., at 19) (emphasis in original). The Act was not designed to govern contracts "in which one of the parties characteristically has little bargaining power." Prima Paint Corp. v. Flood & Conklin Mfg. Co., 388 U.S. 395, 403, n. 9 (1967); ....
The Court has relied on the FAA, not simply to overcome once-prevalent judicial resistance to enforcement of arbitration disputes between businesses. In relatively recent years, it has routinely deployed the law to deny to employees and consumers "effective relief against powerful economic entities." DIRECTV, Inc. v. Imburgia, 577 U.S. ___, ___ (2015) (GINSBURG, J., dissenting) (slip op., at 9). Arbitration clauses, the Court has decreed, may preclude judicial remedies even when submission to arbitration is made a take-it-or-leave-it condition of employment or is imposed on a consumer given no genuine choice in the matter. See Epic, 584 U.S., at ___-___ (GINSBURG, J., dissenting) (slip op., at 21-22) ....
Piling Pelion on Ossa, the Court has hobbled the capacity of employees and consumers to band together in a judicial or arbitral forum. See Epic, 584 U.S., at ___, n. 12 (GINSBURG, J., dissenting) (slip op., at 22, n. 12) (noting Court decisions enforcing class-action waivers imposed by the party in command, who wants no collective proceedings). The Court has pursued this course even though "neither the history nor present practice suggests that class arbitration is fundamentally incompatible with arbitration itself." AT&T Mobility LLC v. Concepcion, 563 U.S. 333, 362 (2011) (BREYER, J., dissenting).
....
Today's decision underscores the irony of invoking "the first principle" that "arbitration is strictly a matter of consent," ante, at 7 (internal quotation marks and alterations omitted), to justify imposing individual arbitration on employees who surely would not choose to proceed solo. Respondent Frank Varela sought redress for negligence by his employer leading to a data breach affecting 1,300 employees. See Complaint in No. 5:16‒cv‒00577 (CD Cal.), Doc. 1, ¶¶1, 59. The widely experienced neglect he identified cries out for collective treatment. Blocking Varela's path to concerted action, the Court aims to ensure the authenticity of consent to class procedures in arbitration. Ante, at 7‒8. Shut from the Court's sight is the "Hobson's choice" employees face: "accept arbitration on their employer's terms or give up their jobs." Epic, 584 U.S., at ___, n. 2 (GINSBURG, J., dissenting) (slip op., at 7, n. 2); see Circuit City [Stores, Inc. v. Adams], 532 U.S. [532,] 139 [(2001)] (Souter, J., dissenting) (employees often "lack the bargaining power to resist an arbitration clause if their prospective employers insist on one").
....
... [M]andatory individual arbitration continues to thwart "effective access to justice" for those encountering diverse violations of their legal rights. DIRECTV, 577 U.S., at ___ (GINSBURG, J., dissenting) (slip op., at 1). The Court, paradoxically reciting the mantra that "[c]onsent is essential," ante, at 7, has facilitated companies' efforts to deny employees and consumers the "important right" to sue in court, and to do so collectively, by inserting solo-arbitration-only clauses that parties lacking bargaining clout cannot remove. CompuCredit Corp. v. Greenwood, 565 U.S. 95, 115 (2012) (GINSBURG, J., dissenting). When companies can "muffl[e] grievance[s] in the cloakroom of arbitration," Merrill Lynch, Pierce, Fenner & Smith, Inc. v. Ware, 414 U.S. 117, 136 (1973), the result is inevitable: curtailed enforcement of laws "designed to advance the well-being of [the] vulnerable." Epic, 584 U.S., at ___ (GINSBURG, J., dissenting) (slip op., at 26). "Congressional correction of the Court's elevation of the FAA over" the rights of employees and consumers "to act in concert" remains "urgently in order." Id., at ___ (slip op., at 2).