Like to add on that I used to raid pretty hardcord back in WoLK. Sever first I think. Like you fights back then isn't as complicated as it is now mostly becasue DMB/Big Wings/WA doesn't have as much function as it is now. Those addon were mostly use as reference but you still have to rely on your experience with the fight look at the cast bar/hp bar. Anyone remember when certain boss would do a huge AoE to everyone everytime 25% of his hp going down? You are to make sure everyone is top off before pushing that.
Now these addons tells you everything the boss does all people do is follow what the addon tells them. I think in SL in one of the raid tiers WA was way to powerful on one of the boss (forgot what it does but blizzard made a big stink about it and remove some API to break the WA people are using).
When addons get out of hand like this blizzard have to design on fights with them in mind and that's not a healthy design. What really blizzard should do is limit on what addons can tell you and slowly close its API. Be more strict on what addons and boss mood can show.
You hardly need addon in FFXIV even in savage raids. Heck a lot of people got ban coz there was an addon that place an extra maker on a platform during p2 in a fight and that's not allow.