I wouldn't really call CBM built for short blitz games. No one really uses CBM for blitzing. We do have a tendency to play games with no more than 20ish players, on maps of approximately 15 provinces per player. But even a six player game can last for 60 or more turns before a winner emerges. But that still means we're playing on maps that can be anywhere from 70 to 300+ provinces. It's not an insignificant range, and MP games don't really get much bigger than that. I think you'll find that CBM was used in the largest games on these forums in the past too, like Kingmaker.
Also what you see as excessive value fiddling in many cases is just the least controversial way to give nations small buffs or nerfs without getting people all upset
And in many cases it can go a long way just making small changes to a few units. Like in SC2 where just changing the max range of a unit by 1 suddenly is a big deal.