Replying to Why are Touring Boot Soles so Soft?

After chewing through a few of the rubber soles on my touring boots while scrambling around in the alpine, I continue to wonder why companies put such soft rubber on their boots. While my ski boots' soles are torn apart, the soles on my mountaineering boots (scarpa phantom guides) are doing just fine, and provide plenty of grip.

So, why don't we see more companies putting harder rubber, similar to a hiking or mountaineering sole, on touring boots? I assume it has something to do with the rubber's compatibility with the plastic of the boot shell?