EDID, CTA-861, and DisplayID are the result of decades of piling layers of cruft on top of each other (CRTs, then LCDs, then variable refresh rates), with different data formats from competing standards committees (HDMI vs. VESA/DisplayPort) with different sets of needs (like HDMI/CTA-861 supporting audio codecs and YPbPr/chroma subsampling originally for home theater applications), sometimes coexisting on the same display (this LG monitor has both CTA-861 and DisplayID blocks).