I think that is to cover the abuse currently of challenges just being cancelled. I challenged several opponents before, and they will come up with some excuse to just say they are collecting equipment or something to stall a few days. After a few days, the challenge just disappears and I can't re-challenge.
Also, what rules will be in place if two players cannot agree on each others equipment before saying "okay"? An example of this would be a stunning build against a Barbarian, the Barbarian will see the build and set Juggernaut passive, the other player will see the Juggernaut passive and change to non-stunning skills. Then the Barbarian will see the non-stunning skills and switch to a non-Juggernaut passive, and then the other player sees that change and sets the stunning skills again, and around and around we go!
Returning to DH specific rule discussion (I posted some similar opinions earlier but I will condense them here):
Against Barbarians, I don't feel the War Cry ban fully justified but I do agree that playing hit and run to reset is annoying (for both the Barbarian and the DH). The Barbarian wins that scenario since they regenerate life and cooldowns faster than a DH regenerates life and discipline in general (non-legacy). Perhaps there can be other limitations to EHP aside from War Cry, because as noted by others, Barbarians will simply use Overpower - Crushing Advance instead now to a similar effect.
Against Monks, I feel the Chemical Burn disables the DH offensive power by too much. My experience against good Monks is with Chemical Burn I win 80% of the time, without Chemical Burn I win 30% of the time; which is a huge difference. The reason is that the duels last considerably longer and I must not get hit for a longer period of time. Monks do such incredible damage with their Spirit spending skills now that, on critical hits, they can 1-shot almost any DH. DH also have no second chance ability, so 1-shot and it's over. Whereas Monks take 3-4 high powered critical hits to take down if they have the EHP (due to Serenity, Near Death Experience, and possibly potions if they stack bonus to heath globes and potions). Also, in general, Monks have higher dodge chance than DH and with our discipline limitations (non-legacy), we cannot win that war of attrition (especially if most hits are simply missing the Monk). I propose either a different change to DH such as Sharpshooter ban, or an additional restriction of Near Death Experience banned with Chemical Burn banned.
Against WD, I feel this match up is slightly in favor of the WD (non-legacy DH), but is not so much that they need to lose both Summon Zombie Dogs AND either Spirit Vessel or Spirit Walk. I propose just Spirit Vessel or Spirit Walk be banned (at the choice of the WD), and leave the Zombie Dogs as is.
Against Wizard, I do admit there needs to be some adjustment for the Wizard's benefit. I propose either Battle Scars or Companion be banned but not both. Banning both adds too much of a benefit to the Wizard since they also have Unstable Anomaly which grants them a second chance. Without a form of mitigating Storm Armor between Smokescreens, this duel will be to heavily in favor of high DPS Wizards (Ray of Frost for example tears through my 1.5M EHP DH in less than a second)!
Against DH, nothing needs to be changed as both players can copy each others skills! Future rules can be made for legacy vs non-legacy however as this still is an open discussion. Again, my opinion on the fact is: if I (non-legacy DH) can 1-shot a legacy DH I will win since they can unlikely 1-shot me; however, if both players cannot 1-shot each other, I will likely lose due to the meta game being simply Smokescreen, Vault, and Impale and no other build stands a chance at higher equipment levels.