With respect, the 'no justification required' stance is itself indefensible. It precludes any serious criticism of the way the 3 game modes interact with each other for no better reason than that was the original concept. Perhaps Frontier can do better than what was set out originally now that the problems are evident.
As things stand it will be more difficult for us to accomplish things in open because of direct player on player interaction coalescing around CG and such like. This will be exacerbated by PP because we're going to be in competition with people in our own factions to stay in the top x%, some or many of whom, will be playing the game with the competitive advantage of solo. This isn't about forcing people to play the game our way, it's about making open a viable alternative to solo, since FD have seen fit to create an expansion which puts players in competition with one another. It makes no sense for players in open to be ranked the same as players in solo when we're playing on completely different terms.
Given that:
1) Frontier had already decided in the three modes, shared galactic background simulation and mode switching before they went forward with their Kickstarter for the game;
2) The stated game design contained in the Kickstarter pitch has formed the basis of what we have now;
3) The game was backed, at least in part, due to the flexi-player nature of the game;
4) The existence of Solo (Online) was used in part to placate those who were disappointed (or worse) at the removal of Offline mode;
5) This particular argument has been going for over two years prior to launch and these core game features form part of the launched game;
6) The game was launched about six months ago;
.... I don't expect them to change this late in the day.
Frontier have, from the beginning of Powerplay, stated that it is able to be played in all modes. As there is no player hierarchy in a power, controlling affiliates of a Power is not possible. Players don't play 24/7, are not all in the same time zone and cannot all be in the same instance - therefore direct opposition to competition is not guaranteed.
You may not be trying to force others to play the game your way but you seek to remove game features that players are currently enjoying - which is almost the same thing.
Regarding ranking, all players inhabit the same galaxy, the same shared galactic background simulation - to have different outcomes of Powerplay in each mode would effectively split the GBS - something that Frontier seem to be extremely unlikely to do - especially given that XBox One players will also all affect the same shared GBS, as will PS4 players.