A capture the resource point RTS is never going to be called realistic in a complete sense, but then again, no game ever is.
The Combat Mission series and Ground Control were great because they weren't resource point based. You started with you your forced, and that was it. It was a real disappointment that GC2 was a resource based game.
But what CoH had over other resource point based RTS games was the combat was more natural/life-like that other RTS games. So I can see why people could use the word "realistic" to describe it. They don't mean that the armour penertation values are correct.
What they mean is that you can set-up a proper ambush (left and right cut-off groups, killing goup), with a couple of MG at either end of the killing group, overlapping their fields of fire. And it will play out like a proper ambush.
I don't have CoH:OS, but reading the reviews, the two new armies are completely polarised to an extend that you don't get in the real world. But you do get it a lot in games, to give a more varied game experience. Games have to me made to hit a large enough target audience to make it worth while. And they have to be interesting of else we leave them
I think playing the UK against the Wehrmacht, and the US against the Panzer Elite might be more natural. Toning down the "special abilities", just as only 1 glider drop a game would make it more natural. But