Great post, Brandis, I think I agree with all the points except the forced limited distance between captain and his bots.
I'm buby, you might know me or we could have seen each other in a match, as I tend to play a ton of captain games. I'm not a newbie.
I think the problem you are trying to tackle with this is obviously legit but really this way of doing it would introduce a ton of issues and just make the game frustrating, in my opinion.
Let me explain, how many times as a captain I was a bit forward my troops, not much, I'm not talking about ramboing or anything, and then got isolated by enemies charging me in a bad spot.
Usually, in those occasions, I will give a final order to my troop to back far away because they might get engaged and I don't want that to happen. Now if we have a bots limit radius, what will happen?
The order might be registered at first and then when they will reach the fixed limit, they will come back to me, or as I die the game might consider I'm out of range and make the units run towards the place where I died or any other unexpected issues that could be introduced by such system, which would be really frustrating.
You will be just switching a flawed system with another flawed system, and people will still try to optimise it in an unfun way, the game will force you to battle or play around as much as you can around this fixed limit in order to be the most effective. This is just frustrating, this will result in the most skilled player trying to fight the game mechanic, min/max it as much as possible, but with an element of frustration added.
It's just an example, but you could make a ton of other better cases where such a system will just ruin your experience because at the end of the day it's way too rigid to account for all the kind of situations that you can have in the game and that has nothing to do with ramboing in itself.
My personal solution to the issue of ramboing, will be to make the bots have 100% in all stats, basically enter god mode when only one or two solo enemy player is inside a determined radius around them (for the solo players trying to abuse AIs).
Such radius will be fairly small around them but will make them super effective, but the process would get cancelled if more enemy units enter that radius around them.
Basically if a cav rambo player enters this determined radius (which would be different and balanced for each troop) and he is alone in that radius. The units will turn god mode and have 100% accuracy, increased efficiency, everything possible to make them kill that isolated player entering their radius.
In the most common example,for a troop of an archer against a solo cav player, as an anti rambo mechanic, they could prioritize hitting the horse and make the player go down his horse (and doing it so with the best accuracy possible if such player enters the radius alone). I'm sure no one will want to rambo solo against archers with a simple change like this.
The RP explanation is that such troop would have to only face one unit or two, so their focus should be through the roof and they should be able to hit the sickest shot and just be the best AI they can be in that scenario.
Such radius would only work or turns on if that isolated enemy unit inside that small radius is controlled by a player, so god AI mode would never turn on against enemy AIs, in order to prevent some other unexpected issues/rare situations where a solo ai will get terminated for stepping in a radius alone.
And if the issue of ramboing is abused by two players getting on the same troop at the same time, maybe the god gamer AI mode threshold could max out at 2 solo players entering the radius of the troop, it would be a balancing act that would take some iterations, but imo would be fairly easy to implement and way less frustrating and problems inducing than limiting the distance between the captain and his troops.