So early on blizz kinda didn’t really know what to do with raiding big example is molten core was literally made in a week thats a real thing. So they never really made any kinda base mechanics of knowledge on how to deal with debuffs and the sort. Now early on mods fixed this and basicly from there and early on blizz designed around the popular mods existing for everything so the game has never really gotten to much in the way of base stuff on telling you whats going to happen. Its just how the direction their development went early on and is now fully expected to happen. With the mods blizz has kinda ignored aspects of the game to improve because well everyone uses the mods so theres no need to and at same time with the mods really good tracking they can go way over the top compared to other games.
Its mostly just a weird situation other games try to stop mods or don’t really like mods like DBM and do not design around it. Example of this is ff14 they have designed alot of mechanics thats easy to identify in base game and their extremes you rely on boss movements to know when mechanics pop out. Wow on other hand is the opposite most bosses don’t have alot of indicators in comparison (they do have some just not as many) and instead rely on the mods tracking to let players know when big stuff is about to happen and so forth. Its to far in development of this game to go in another direction without revamping the entire game and its functions which at that point it would be better to just make wow2 which isn’t going to happen.