You get interesting multi-sided PvEvP conflicts
It might seem like that happens, but... history shows otherwise. Atlas for example just recently released extremely overpowered rewards for killing the NPC content in the game. As such, you could say "look, interesting multi-sided PvEvP conflicts!" which... happens at first. And then the large groups swarm the areas and camp the area and no longer is it a multi-sided event. It's just a farm spot for the biggest population group to sit on and mindlessly harvest the best loot.
In addition, that kind of gameplay has only worked in relatively small games, in terms of server population. With 100 people on a Rust server, having an event that might focus 15-20, with the event happening multiple times a day 24/7, kind of works. People do go and fight over the loot. However, when it hits larger scales, such as Atlas and so on, the 100 people in the area are all in the same group eventually. No longer is it a multi-way fight. No longer is it a bunch of people fighting over something. Everyone gets pushed out by the most populous group.
Now, I can still see this somewhat working, as long as respawns are not spare-endos as I've covered in other threads (and will continue with a fresh one soon I think). But that might not change the result too much - the larger group will just sit on the spot and take everything. Keep in mind, the reward needs to be great enough to lure people in in the first place in order to be a valid mechanic that gets used. As such, the group that can perma-farm that content is just going to get 'free stuff' from these events much more than anyone else, tipping balance scales even more in their favor.
At the root of the problem is time. Time is the ultimate equalizer. As long as players have to put in the same time, no matter the group size, for the same relative results, then the game is balanced. If some group can perma-farm free NPC loot from the game world, they're saving on time, because in order for that loot to be worth it, it has to be more efficient than any other method of farming that those players could do in that moment. So they're getting efficient farm for free by camping these NPCs, with no extra expenditure of time. Again, if the reward is less than what you'd otherwise get mining, there's no reason to go for it. If the reward is perfectly, 100% balanced with the time cost of mining, then again, it just gets perma-farmed because it's less overall manual work.
Again I'm relatively neutral on the idea, and I do see some inkling of a path to some sort of balance, where the content is just not rewarding enough to send in 100 players to go for it, but instead, is optimal for a group of 3-5 to go after this target. Still, a larger group, bored, will throw out optimization and send 10-20 people for this lower reward, even though inefficient, just to do something and to win and scrap everyone else's dead ships - perhaps making the extra manpower worth it after all with the salvage. That might be good enough, but it is tricky in terms of how it works when people can field such large numbers like what will exist in Starbase (as it does in Atlas).
If the large group of 20 people goes after the NPC events in Rust, they get quick stockpiles of C4 and Rockets and weapons that no smaller group has the ability to compete for really - you better bring your own group of 20. A smaller group cannot even match the amount of value from those events, if they just wanted to "out farm" their enemy. Without being contested, the larger groups snowball into being able to raid everyone around them with these free rewards that normally take a lot of time and effort to harvest from the game world. The area around the large group is quickly cleared of all smaller bases; often times the group becomes so 'wealthy' they just blow into any base just because. If each use of C4 or Rocket was instead representative of work that the group had to expend to create, then there is more choice involved, and less blowing into random bases just because.
The end result for Rust? 1000 servers with 1000 different rule sets. 2x, 4x, 10x harvesting! I know EVE had success with NPCs to fight, so it can work to some degree. I'm just not sure if it works for Starbase though I'll keep pondering it for fun.
NPCs should be hunting you because the server knows nothing interesting has happened to you in a few hours.
This reminds me of Elite: Dangerous where you're just trying to get somewhere and some random NPC AI event triggers and pulls you out of frame shift drive and annoys you for a moment before you continue on your way. It is not really fun overall to have this kind of thing happen; frankly, it is annoying. It is better that if someone wants to be left alone, they can seek that isolation in the void of space.
I do however recognize a lot of people are familiar with that and feel it is more approachable to fight easymode NPC opponents to satisfy the need to pull a trigger instead of fighting other actual players. I do not think it is a necessary component to the game however. Planetside 2 for example has no NPC AI to fight - having enough people in the same area with the right objectives, and you don't need it.