HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

Nah, no need to be so harsh. He probably meant that even without Alt, everything should be transferred, just a bit faster and easier.

Yeah, how much faster could Ctrl+Alt+Shift+click _on_ the stack be? :)
And it's clear – just make a single button for "move right/left," and keep the number 1 key as the fastest, but with the lowest priority.
But there can be different situations – for example, I have the last Pegasus or a Fly in my army; these units aren't just for rushing, but also for the first turn – so they should stay with the enemy, not move further down the chain, so I'd have to click again.
Or, several Angels, and I want to rush the enemy with one of them to extend the chain.
Not to mention (possibly) the headache for the programmers, and there could be all sorts of awkward situations, besides the ones mentioned above.
And in general, full control over the process is always better than automation.