The biggest benefit to stack over a cloverleaf is that cloverleaves have this issue that the same lane needs to be used for offgoing traffic to decelerate and oncoming traffic to accelerate. There's a partial mitigation for cloverleaves, which is to lane segregate the ramps so that there's less pressure for traffic to have to accelerate to highway speed immediately, but stacks eliminate the issue entirely.
Driving around the bay area, it seems that 90% of traffic is caused by shared onramp-offramp lanes, or insufficient distance between them.
Many highways otherwise would have much more capacity. The telltale sign of exit issues is highways that bog down to 15mph for a couple miles, only to open up to 60+ with the same number of lanes.
Total shame and often unnecessary. I wonder how many man-years are wasted as a result.
