Probably those people who tank and just run up to mobs and flash probably watched videos or other tanks so. For me I know the range of flash so I can run up to mobs and be sure to grab all if not most plus the healer and dps know whats up so they don't attack/heal making my job of grabbing aggro easier.

However when I play on my dps I am noticing a trend of tanks running and waiting for their auto attack to go off then flash or OP. Im not sure where this is coming from but it needs to stop as that is not how you tank. Imagine if the same person did that in end game content. Other players will get angry at them for not playing their class properly then they will come on the forums and flood it with "this community is turning toxic" threads