Infi and SR77 are so tough that they can get away with through hardening on high-impact prone blades, i.e. choppers.

All of the larger SR101 knives (over 7") are differentially hardened to leave the body of the blade softer and the edge harder. The softer body gives the blade additional shock absorption and toughness. On blades that are not realistically going to see a lot of chopping action, through hardening for SR101 makes sense.