Well, the Pits are used as training grounds, like the Greater Rifts were in D3, and after you’ve cleared Pit Tier 70, for instance, Torment level 4 basically becomes redundant (Because Pit Tier 70 is equivalent to Torment 5). The Infernal Hordes difficulty level is whatever you have set your difficulty at, at the moment, where mine would be Torment 4. And this is where the problem is. You can’t really progress anymore, like you otherwise could up until this point.