Even RNG mechanics have a visual action the boss makes before the move is executed or it has a cast bar. Most of the fights in this game are heavily scripted though with very few RNG mechanics. This was just a poorly thought out way to deflect the question because you know what the answer is. There is no difference. In then end you should be able to react accordingly when you see these actions. Some people lack the attention span or reaction speed to do this and benefit from a call out on the mechanic more so than others. But in reality there is no difference between cactpot/act calling out a mechanic and a person over discord calling out a mechanic.