Sure, and what I’m saying is that part of what makes real world commanders great is that they know, through experience and intuition, what that modifier would be, more or less. They'd know if it was a big impact or a minor impact, if it was worth risking for an advantage somewhere else.
That’s true of gamers as well – the better players know what impact a flank charge will have, either by knowing the number, or by seeing how lots of flanks attacks have worked over many games. The difference, though, is that if the general is correct he knows something about how war really works - that is a clear skill. If the gamer is correct he merely happens to be on the same page as the game designer - that's just sharing a bias with a designer, it doesn't mean you're actually more skillful.
I’ve played so many bizarrely designed computer wargames that I’m now very sceptical of following real world tactics (as I understand them), and just hoping that the game takes all those factors in to play.
And it also removes the ability for games to teach me new strategic concepts. I just learn a bunch of good enough strategies, dismiss the bits that don't fit my own understanding of war and move on. But if the actual rules are given, and then it goes in to detail about why those rules are in place, maybe in playing the game I'll get a new insight in to some battlefield factor I didn't understand before hand.
However this is also a matter of the command level that you want to portray in the game, so it's a matter of design objectives, not a point of principle.
Sure, but the point I'm making, about game mechanics playing out behind closed doors, leaving players guessing about what tactical principles they should be applying, probably holds even more true as you go to higher levels of command. There’s a temptation to have more and more complexity underneath, but that’s okay because it doesn’t slow the game down because it all happens in the background. But if my right flank is routed, I want it to be because I made a bad call, not because I wrongly assumed that high ground gave a combat bonus, and that the moral impact from a flank attack was much greater than the moral impact of having my best commander in the area.