I was thinking the same thing. Blizzard explicitly allows this kind of thing but most games do not.
Even with DBM - there used to be an addon that told you exactly where to stand to avoid different bosses attacks. That got banned pretty quickly because it over trivialized the mechanics.
For suresies. I didn't play in Firelands but I heard some stories of the "drawing football plays on the ground" era. We used a similar addon for Sha of Fear p1 side platform but it displayed where to stand on a HUD, not on the actual floor.
Competitive PvE exists too (speedruns, world first races, etc). In FFXIV mods are less tolerated and while some raiders use triggers (TTS voice lines triggered by enemy actions or friendly buffs to tell you what to do), many consider it borderline or actual cheating, while others are fine with it because it's similar to having a player do it (ignoring perfect accuracy and no brain capacity used). So it's a controversial area.
Even with DBM - there used to be an addon that told you exactly where to stand to avoid different bosses attacks. That got banned pretty quickly because it over trivialized the mechanics.