I just think that level of control of your units should not be automated. I agree that whoever has the faster clicks should not always win a fight and that sniping is not a desirable meta, as @BreakfastBurrito_007 pointed out, but can we let the-fine tuned control of units remain a learnable skill?
there is fun in trying to find the lowest HP cav that rushed your early eco and being able to kill it as they retreat.
Also there is fun in sniping if you know it will be effective because you have learned when it is effective.
Adding a stance to do automatic sniping will add a level of automation that doesn't fit with the behavior of other stances, or any other configurable behavior in the game.
Also, when the sniping meta is fixed, automatic sniping will probably just mislead new players into thinking ranged targets should be prioritized, when in reality it depends on many more factors.
perhaps you would take interest in attack ground? I would find this to be a much more generally applicable attack mode. Its got a few nuances in terms of implementation, like how to smoothly choose the radius while selecting the area to attack, and whether or not the attack should be one volley or endless attacks.