The problem is that you end up with a massive pool of garbage.
The Interior Council will also give you retirement stratagems, so you can get rid of the complete deadbeats. That's not easy to do, if they're powerful people already (have a lot of seniority). But that's just what you'd expect, right?
Most likely, if you want to gamble on a bunch of young leaders, they would also be easier to dump. You'd need to fund the Interior Council well. And you'd need to balance money, PP, and the number of cards you've got for both hiring and firing. Nicely complicated, huh?
I've also heard that you can kill off terrible leaders by putting them in an OHQ position and sending them to war. Indeed, DasTactic warns against putting really good leaders there, since they tend to die quickly (even when you don't send them on suicide missions, apparently).
My own - limited - experience doesn't match with that, since I've never lost an OHQ commander in battle. But then, I haven't been trying to get them killed. So, who knows? That might be an option, anyway,... provided you're evil enough to want to do it.