X is a sandbox simulation, getting that to multiplayer would need a lot of work, and certainly its not something you will enjoy if it is just retrofitted by modders, since the sandboxes will desync for each player (if you only add “basic multiplayer” like say the GTA2 multiplayer mods), the game needs to be designed for that, and i think X is intentionally trying to keep it a local simulation (since it has its benefits in how much complexity you can show the player).
so no, X is great since the simulation can be altered (by you) and expands, as you play, much like original elite did, but you cannot simply “make this multiplayer” I’m afraid.
Citizen will contain the ability to create your own servers/sandboxes, but that’s just hypothetical at this point; while Elite solves it with their P2P / group system, which is also yet far from perfect, but in both instances, you have some kind of “servercode” for the more “data intensive stuff” like storing all trading / world state data, and yeah, that data tends to explode
and designing network code for dynamic data like trade and ai movement, while keeping it fun to fly the spaceships and see what other players do at the same time, is quite some work and has its technological limits.
this is why eve gameplay is so slow paced, however, that is only needed since you have huge instances with many players, i am sure, if X would want to, they could do a coop / small server version of their game so you only play with 3-4 people, but it would need to be designed for that from the ground up, not patched in afterwards (similar problem of kerbal space program going mp); which explains why elite is designed, like it is designed. every solution brings up problems, its a stone paper scissors lizard spock game with the networking.
And welcome to the basic problem, why the Bell guys built unix back then. They also wanted to play their space trading game together…