Or neither, I might just have a different opinion to you.
I don't want a storyline in a sandbox, they just get in the way. The difficulty setting is in ship/outfitting and mission choice its as easy or as hard as you make it.
What anchor ?. There's nothing missing, it's all just optional player choice is great. Don't sweat other peoples mode choices, they can't be forced to play with you anyway.
That's just your entirely subjective opinion. I think the game provides solo, group and open to suit whichever mode I fancy at the time and they all have their individual advantages without detracting from the others.
I like all of the modes, and in a genre like this you can't overspecialize so it makes good sense to cater to everyone which the modes do perfectly. It's only an issue for the people who resent or worry about other peoples choices, which they can't influence anyway. Totally pointless self inflicted issue.
You are ignoring the situation entirely to fit your desired reality.
Nobody wants a narrative with a sandbox. But that's what we've been given. The existence of the narrative can't be ignored because it limits what the sandbox can do and vice versa.
Difficulty settings aren't about picking crappy components to make it harder for you. The NPC's dont get smarter or dumber based on what ship you pick or what weapons you pick. Difficulty != handicap.
Nothing is missing? So you are blind and dont play the game, good to know. I'm sure everyone playing powerplay (which is the most multiplayer sandboxy aspect of the game by far) has been extremely satisfied with all the multiplayer features and how much control the participating players have had in steering the story that they are creating thru their actions. Oh wait, no they're not. Because _EVERYTHING_ that is multiplayer is optional. The very essence of it being optional means impotent.
It's not about forcing players to play with you. In a hypothetical multi-player only game, the people playing it would be opting in. The difference is that _everyone_ playing it and impacting the game is directly able to be impacted by other players doing the same thing. Instead of the shadow nonsense we have now that makes most if not all multiplayer efforts meaningless.
In that same vein of hypotheticals, a single player game would be just that. You impact your own game and nobody else's. Free to do everything and anything you want.
What I've stated isn't subjective. It's observed reality. Anecdotal, maybe, but with a sample size that is far larger than whatever anecdotal evidence supports your idea that it's the best of both worlds. I dont see people praising the single player aspects of the game, only complaining about how aspects of multiplayer are interfering with them and always potentially destroying their ability to play solo. I only see people complaining about the lack of multiplayer functionality that can never succeed because it all has to be optional, even in open.
And as for overspecializing, making a game single player or multiplayer isn't overspecialized. It's normal. There's a reason why most games dont go the route that Frontier went with elite dangerous. it's because there are too many mutually exclusive needs and wants in either mode and when you eliminate those, you are left with compromises. Compromises in both that can never meet the potential of either if they were done individually.