They tried that and no one liked it so they stopped it

I think, entirely taking away any sort of detection, especially when viewing the long TTK as set, would not work either. There needs to be a downsight to hiding all match or holding angles. Being marked on a map for a while when shooting someone from some hideout would be one. This way, the surprise moment stays, but you cant simply run away and immediately try the next angle, because now - even when you managed to kill someone - the rest of your opponents will have the advantage in the next engagement and punish the next attempt.