An educated guess ...
The standards were set by the three "A's", Adobe, Aldus and Altsys and commonly accepted by the huge number of customers who bought their software. Corel has little or nothing to do with early standards and was initially introduced as a graphics solution for early Windows OS's while the 3 A's were mainly Mac applications.
In case you're not familiar with Aldus and/or Altsys: Aldus published PageMaker and Freehand although Altsys actually wrote Freehand along with Fontographer. The chose to license Freehand to Aldus and to publish Fontographer themselves. The three companies dominated the early print and graphics markets and together agreed on the PostScript language as a standard for data communication between computers and digital printers. Among other things, this agreement led to the EPS (encapsulated postscript) file format as well as the PostScript Type 1 and Type 3 font formats.
As things evolved, Adobe bought Aldus which Altsys then had to sue Adobe to get back their rights to Freehand. Altsys then sold out to Macromedia who was eventually also bought out by Adobe.
