Did I say something about holier than thou...?
Mobius' group is a good example of how a pure open PvE mode should exist as well (change solo to open PvE and be done with it..). It's quite clear that the current game modes are insufficient.
EDIT: It took me a while to understand how pointless your suggestion of a PvP group is

How would that work exactly? If I spot a Hauler we kick him out?

What prevents somebody to go grind some CR in solo and come back in a pimped Viper? The thing is, PvE doesn't need to be regulated as it is already regulated by the game mechanics, PvP on the other hand needs strict regulations for it to be fair and balanced.
Reading these and similar comments gives me the feeling that the way the game works is not fully understood by everyone.
When you log in, you talk to the ED servers. They retrieve information about your ship and the location you are at. Based on this, your local client renders for example the space station you are at. Also, information about NPCs hanging around is probably provided by that data. The rest, how those NPCs are flying, when they potentially open fire on eachother, etc... is all handled by your local client. So with a little data (very narrow bandwidth neccesary) your own computer makes everything else happen. Important changes, for example, getting a bounty on your head, or selling cargo or getting missions is exchanged with the central server.
Going into SC (or dropping out) are moments when information is retrieved about what the local client needs to render, but every thing else is done locally. If you are fighting an NPC, it's your own computer trying to kill you, not the frontier servers.
The reason there is no offline mode is that, while data from any transition is small, the total amount of information in the universe us huge, so it wouldn't comfortably fit on a local computer. (I have no idea how big, but I imagine terrabytes, so not realistic to ask this of anyone's computer, let alone the weeks or months of download time for the client)
Now, all this data consists of a single instance of the universe. So tracking how many goods are available at a station, what affiliation it has to the three factions, what part of the universe has been discovered, all that is the same for everyone. Regardless of the mode, we all play in the same instance with regards to the data that is held on the servers. If the price of a commodity drops at a spacestation, it drops for everyone, regardless of mode, because when your client contacts the server to retrieve the price, there is only one instance available.
Now with regards to seeing other players: Since having everything bounce over the central server is a networking nightmare (keeping track of your flightvector and all the changes to it needs a hell of a lot more bandwidth than just the information of rendering the instance), this solved by doing this through P2P. When you see another commander, the information is directly exchanged between your and their computer. Handling the bandwidth is your and their responsibility. To make sure that this doesn't spoil the experience (with lag), instances are created with a maximum of 32 players. When you have 32 players in an instance, you have 32 computers talking to 31 other computers at the same time. That is 496 concurrent connections (if I remember my middle school math correctly). If a few people have a flaky connection, you can imagine the frustration of those players.
Since those connections have to be fast, they use ping times to decide which players should be together in an instance (for example around a station). If the ping between two players would cause their experience to be unpleasant due to lag (for example a player in the UK and in Aus), those players are not placed in the same instance. This is what the matchmaking does. It tries to keep instances as pleasurable as possible for everyone (based on their networks)
What groups does is limit the people you can see in an instance. Only those in the group are even considered for matchmaking. But there is still no guarantee. If the network times would cause troubles, you still won't see eachother. Friends tell the matchmaking engine to, if at any way possible, to get those people in the same instance. It probably lowers the threshold at which point the matchmaker decides that it no longer makes sense to put two people in the same instance and allows for more lag (meaning you might see your friends ship outside the station while he is already inside on his own computer) because the social experience will hopefully outweigh the reduced reliability of what you see.
Now to get back to the arguments we are having about modes: Mobius does not use a separate instance of the Elite servers. It just tells matchmaking which people can potentially see eachother in an instance.
Likewise, if people who like PvP were to set up a group (don't know if one already exists), it would mean that the people in that group are far more likely to meet others who enjoy PvP that for example in open. So creating a group like that would mean more PvP that for example in open, because there you might meet someone who will just run away.
Basically, open is: everyone that is not in a group or in solo. If people in open have a large friend list, you might still not see them, because they keep getting matched with their friends and not with a random commander.
Groups, like Mobius or a PvP group filter and make sure that if you are matched to another commander, they will share the same preferences (based on what the group is created for)
Solo just means that the matchmaker doesn't need to bother. You only retrieve data now and then from the servers to create your instances and that's it. No communication with other computers.