Player skill level and practicing skills specific to PvP. You've already admitted ladders would be a good idea. Without ladders being the case, this is an issue you've said is a problem. A PvP would know to circle while blocking and then BS, or to swing for shave damage to hopefully hit and negate the BS in that case, which could allow taking advantage of lag or mildly mitigate it.
You're free tell tell everyone how all players behave exactly like PvE enemies. You're free to explain to all of them how they won't learn their skills to complete PvE if they don't PvP. You're free to explain to people that all of the time wasted fighting is worth the skills for wasting more time fighting in PvP.It is just flat out disingenuous to claim that there is no meaningful PvE takeaway from PvP combat.
Even if you are saying it's entirely fair, you've already admitted in this post they can learn the PvE relevant skills playing PvE.