I don't think I'm ignoring it. Perhaps "technically" was the wrong word to use? I can't think of the proper one at the moment if I got it wrong.
There are flaws that interfere with Open working as it should (for the purposes of competitive gameplay). These are unfortunate, they exist, and I'm not ignoring them. However, if every one of those problems were somehow magically resolved, mode switching would still remain as an in-game "flaw". If everyone had perfect (fast/reliable) network connections, perfect software, reliable power supply, all played at the same time, and whatever other issue there may be... switching to Solo for the purpose of avoiding PvP threat remains as a difference.
I don't see instancing (excluding networking issues) as being a problem. Players are just grouped into small chunks. A war is rarely fought on one battlefield.
But you still seem to be unable to acknowledge that the thing that decides these PP and CG events is relative number of players on each side, pure and simple. That's far and away the biggest imbalance - the decider - even if everyone was in open at the same time and everything else was perfect - that everyone seems happy to ignore.