You have to realize that about 75% of that is just random raid damage, the fact that there are 9 bosses in the encounter means that there should be AT LEAST 9 different random throwaway "hits x player for y damage" or "hits all players for y damage" abilities. Some of those mechanics can be summed up as "you can't tank both Xaril and Kilruk" or the other pair. So basically the mechanic is bring 2 tanks. A few more are literally just "use your active mitigation" or bad things happen (parasites from Rikkal). Amber and Bloods are the same mechanic (burn the add before it heals the boss). These are all just examples. I would say Aim, the Catalysts, Mesmerize, Shield Bash/Vicious Assault, and the charge mechanic are the only real things that are actually important in this fight. Otherwise most of the abilities (including calculation, hurl amber, multishot, etc.) are just extra raid damage and almost irrelevant in terms of strategy on normal.
Also, nice job comparing probably one of the most complex bosses in the game to one of the simplest ones. If you look at Immerseus, it's literally 3 mechanics (tank swap, swirl, kill/heal adds).
More mechanics is almost always a more interesting and fun fight for me. Siegecrafter, Paragons, Garrosh, H Dark Animus, H Durumu, H Spirit Kings, and Ambershaper are some of my favorite fights in the game, and yes I have played since Vanilla (didn't raid until BC unfortunately).
Edit: The post I quoted was the entire dungeon journal for Paragons. I snipped it.