Because it's really about easier coordination with your mates/associates. For want of a better term - think of a social club with common goals and shared activities. Those might be aligned with game lore (such as pro-Imperial/Alliance/Federation groups) and/or fit into wider mechanisms such as powerplay.
The in-game tools relating to this are, frankly, awful. It can be bypassed to a degree with 3rd party tools but the point is that it shouldn't really have to be that way.
This line of argument for better team oriented tools ingame, total , sorry, but the fact is, it's total .
20 years of being in the same group for online games across multiple genres and games, most of which had NOTHING to support to teamwork, groups, or anything related to them. Never been an issue, even before the 3rd party tools that exist TODAY to facilitate communication were created, their predecessors did exist and we used them. We had voice comms, Roger Wilco, we had chat tools such as IRC, and we bought our own domain to set up our own website, complete with our own email addresses. One of my COs still pays for the domain, got some placeholder stuff up, one of these one of us might do something for it, but we've been saying that for a decade now, so...
HO CG, a FB group was created, BOOM! Instantly able to communicate with each other, I'm still part of the group, it's still quite active. Took a few minutes to set up and cost..nothing, no one had to install anything and it didn't increase the game's footprint 1 byte, nor did it alter anything IN the game that might ruin someone's immersion(which frankly I find to be one of the biggest whines around, it's a game, if you get THAT immersed in it, you need help, and this from a guy who learned to speak drow for a Neverwinter Night persistent server I helped GM on, it IS just a game!)
So, tools from the game to make communication and coordination better? Not needed. Better tools for teams, well, if this WAS actually a multiplayer game, that would be nice, target my teammate's target, stuff like that, love to have it, it's useful sometimes. Thing is, this is NOT actually a multiplayer game. Yes, it's massively multiplayer, in the strictest sense of the words ONLY, as technically, it fails horribly at being massively multiplayer, 32 people MAX per instance? Come on, that's a joke right? There ARE indeed thousands of people online in the game at any given time, so it is technically a massively multiplayer online game, but ONLY technically. There is NO multiplayer game design, Wings is an add on that no one asked for, remember? Much like CQC, lots of whining about it when it was announced, remember? And Wings is mostly a joke, groups of 4! OH BOY! Oh, can't actually get missions for the GROUP? Can't actually share anything with the rest of the group? Hmmm, so, it's not actually a MULTIPLAYER game, it's just a game that allows you to play alongside others online.
They speak of being able to randomly encounter other living players, being able to join up with them if you want, might be risky! There is nothing about forming TEAMS, nothing about GROUPS, just random encounters where you may or may not join forces for a short time. English, do you even? This is a PvE game, the design is very clear, and it's a single player game at that, again, the design is very clear. You CAN randomly run into other living players, you CAN join up with them if you want, but their own advertising suggests that's not a safe thing to do, FD actually DISCOURAGES working together with their own adverts for pity's sake, how the hell can you miss that? And to say it PROMOTES teams and working as a group despite their own adverts giving the exact opposite suggestion? Again, English, do you even?