@Macintom Let's do a mental exercise to see what logical conclusions we can come up with.
So when users played 1.10 on battle.net and patch 1.11 came out, should Blizzard have deleted their characters in order to make them start over and guarantee that no items are moved over? Basically in battle.net that doesn't need to be done since you can just move the characters to Non-Ladder, and start a new Ladder season which is just stuff in that patch.
For Single Player, there is no "Ladder Reset", but like you said, it's about "discipline", so you can simulate a ladder reset by starting all over again. However, the non-ladder characters on the new patch don't get deleted or anything, but they still remain on the new patch. Which means two things:
1. Old patch characters can be time travelled forward and played on the new versions (Which basically equals non-ladder)
2. New characters on the new patch can be either "non-ladder" or "ladder" depending how you want to do it. If you make a new character on the new patch that is "non-ladder", then you can share your items with your existing items (1.07, 1.08 items etc), but if you decide to make a "ladder" (requires discipline) char on the new patch, then you basically have a completely separate single player stash for that specific version.
3. When you decide to do another "ladder reset", then you can take all of your previously created (and separate) "ladder characters" and merge them with your old non-ladder characters, and start all over again with separate ladder characters/stashes for that version (or for that new ladder run).
So this could go either way ;D. A lot of people in the SPF might just decide to say "Oh well then I will just do "non-ladder" single player time travel" haha.