Adobe was simply the survivor (and better business organization) of the original Three A's ... Adobe, Aldus and Altsys. The three of them, according to a conversation I had with the president of Altsys, agreed to accept Postscript as the standard language all their programs would share in common. The result was the widespread acceptance of Postscript as the industry standard for file sharing.
For those not familiar with these companies, Altsys developed Fontographer and Freehand. Aldus developed Pagemaker and licensed Freehand from Altsys. Adobe acquired Aldus and Altsys had to sue Adobe to regain control of its Freehand product. Altsys was subsequently acquired by Macromedia and Macromedia was later acquired by Adobe.