The fact that Elite Dangerous has the "MMO" tag always seemed weird to me because Elite Dangerous is not what you would expect from a traditional MMO; there aren't formal events/activities that you can do with a group (other than winged missions) and there are no team dungeons or stories you can complete with other people. Players can make their own factions, or they can join squadrons that support NPC minor factions, however no matter how big your faction gets "nothing" really happens. There are no benefits to joining player-made factions outside of the social aspect, you don't get access to new engineers, materials, or ships that only people that are part of a faction (or part of faction that controls certain stations/planetary bases). Faction members can't even come together to contribute to their own faction CG to make their own capital ship (with the limit being one capital ship per faction) or to secure outposts/stations/planetary bases to first give their faction the capability to build their own capital ship. What's the point of building the capital ship? So we can fight the thargoids with it, so we can fight other factions with it (player or NPC); being able to pull in your faction's very own capital ship into a CZ would be pretty great.
In other words, the only reason ED has the MMO tag is because, technically, you can play and do activities with other people. There is very minimal gameplay that is actually GEARED toward encouraging team-play.
Yes, I know ED has instancing issues that are sometimes mitigated by being in a team (I personally have had no instancing issues yet, but I've only been in a 4-CMDR team twice).
And I think that's one of the reasons why a lot of people (including me) get fatigued with the game after a certain point, because there's nothing compelling to do with other people. People make good points regarding how the game is a really wide but not very deep regarding other activities like mining, but I think the wide but superficial BGS is what hurts the game the most out of all the other activities that are likewise superficial.
FDEV have done a great job in making a great SP sandbox experience…but without any kind of significant MP experience outside of CGs, the SP sandbox experience is hard to sustain (outside of deep deep exploration, which takes a long time to begin with) without constantly adding more and more short-lived content (like the aforementioned ship interiors).