This is retarded

[Dr3am]

Speaking from direct experience and with a clear memory of pathing behaviors back in the day, I can say that there was not a time that you would lose agro because you were too far away from a mob. In fact- the entire hallmark of EQ was that you never lost agro until you left the zone. Making it otherwise would be ridiculous and destructive to classic gameplay.
What WOULD happen when you got far enough away from a mob is that the mob would begin to find 'creative' paths to get to the puller. This would result in the mob shooting off sideways in various directions, or sometimes deciding to go backwards away from the puller. Said mob would continue to hand off their agro to social mobs along the way, and eventually an entire zone would get all riled up and a puller may not be aware of it until BAM a huge train of mobs decided to find a path to them. The biggest example that I can recall of this was in the Plane of Fear.
I can remember many times in fear where my raid would be meditating waiting for a pull and a mob would come from far away straight at the group- we would then all have to camp out because we realized that someone had the mob on agro and wasn't aware. This happened because fear is a large open zone and thus mobs had a ton of choices on how to get to the puller- or more accurately Verant didn't have the best coding in the world so their pathing AI needed some work.
This didn't seem to happen in indoor zones as the path choices were more clearly defined and therefore mobs wouldn't get lost like in Fear, Burning Woods, or Dreadlands (where it seemed to happen more commonly).