There's a bit of a design philosophy thing going on there, and it's an interesting one.
As a note - when I say 'NPCs' here I mean 'none hostile ones'.
On the one hand - you have an extreme where all the npcs are far weaker, far less powerful - in every way, than pcs. The presence of npcs, in short, means nothing at all. This is good because it allows a lot of PC freedom, but bad because it tends to be harder to enforce setting standards, with anything but ooc work. It also, imo, makes it harder to run interesting events. It has the ability - sadly, of making the setting less immersive in some ways. It gives a lot more player freedom, but at the cost of immersion, and complexity of story. Your world only becomes as good as your players are all at telling a cohesive narrative. Whilst I dont' think Arelith is an extreme of this, I do think it leans more towards this angle.
On the other hand - You have the extreme where all (or most) of the NPCs are far stronger than the npcs (either in soft or hard power) This leads to a more structured and more immersive world, and an easier time in some ways making DM plot, forcing players to have to think carefully before upsetting certain npcs. On the other hand - it can also be much more restricting, much more frustrating. It also - as an aside, is a lot more DM reliant. I'd catagorise (with all love and respect, because I do think it's an awsome server) Ravenloft as a little bit more like this.
Both approaches absolutly have their benefits, but both have their drawbacks. Ultimatly, Arelith is very much meant to be more about the PCs. You guys have a lot more power than in some other servers - and honestly IMO that's a good thing? We can of course- as Twohand mentioned, bring out npcs to defend settlments - and often we will. But this too is (at least in my opinion) a double edged matter. Sure, I'm happy to bring out 100 high level npcs to help fight off the underdarkers, but some of those will be slain in battle and they may NOT return to life.
This too shall pass.
(I now have a DM Discord (I hope) It's DM GrumpyCat#7185 but please keep in mind I'm very busy IRL so I can't promise how quick I'll get back to you.)