I think people who say this stuff either haven't completed a raid on mythic (heroic) ever, or raid entirely in LFR.
I would really love to see any guild complete Archimonde Mythic without an addon tracking the lazers. They would have to run only rogue melee, and all range would have to be wearing stamina trinkets and be spam healed in 735+ ilvl.
Sorry but some mechanics are just too ridiculous. They are designed WITH addons in mind. If you honestly think Blizzard designs their mythic encounters with no addons in mind, you're crazy.