Long time Solo player here, Frontier: Elite II was what started me off 25 years ago and it's nice to be in your own little universe. But something unfortunate happened to me the other day after restarting my character save for EDO...
On creating a new character save, you're put automatically into Open, something which I didn't realise, even after playing ED since its' 2014 release. Spending a few hours doing my own thing, I then got a Restore mission, got to the settlement, killed all the raiders, put the Power Regulator thing into the other... thing, settlement powers up and I start running around refreshing the atmosphere in the multiple buildings.
In among all this, there's one NPC left, I can hear him outside while I'm trying to put the 2nd fire out. Fire out, ok. Then, there's an alarm that the settlement is being powered down. NPC must be trying to stop me, ok, back to the PWR building.
Get there, trying to figure out what's going on, then I see the NPC lurking about. Start firing, his shield will not go down. He fires back. We scrap, he eventually kills me without a mark on him.
It's then I find out that wasn't an NPC but a CMDR. I have no idea why they were there, but I'm assuming it was them who'd removed the Power Regulator. I'm dead with a 100k fine (which I couldn't afford and had effectively locked me out of the starter system) for quite innocently firing on them first believing them to be an NPC, and a mission I'd spent over 40 minutes on ruined.
Because this can happen in Odyssey (people turning up at locations where there is a mission occuring and being able to interfere), I'll be staying in Solo. Sure, it's "emergent gameplay", and it is cool in a way that it's possible, assuming it's not just griefing, but if you just want a quiet life like me, Solo - or a private group with friends - is the best place.