It is entirely reasonable to limit the spectrum of playable characters to those who have some motivation to play the game with the other players. Stealing loot will reasonably upset the other players (not just the characters), by reducing the ways in which they can play the game. So no, it's not just creative freedom, it's being a dick. It's choosing to be a dick. GMs telling you not to do that aren't just limiting your creative freedom, they're telling you to stop being a dick or they'll stop playing with you.
There's a funny thing about Darkvision, since depending on the exact game and edition you're playing, it doesn't always even work in dimly lit rooms, only complete darkness. Which gets a bit silly, sometimes.
Anyone can swear an oath. Sam did not swear into the service of a particular divine order or similar.
In this case it was about twenty-to-thirty-something archers.
My mythic Arcanist defending the citadel of Drezen from demonic assault: "I didn't ask how many enemies there were, I said I cast Cone of Cold."
It's always been normal to me. I tend to get a bit annoyed when webcomics don't have their own site.
Hey, it got me linked through to your site, so that's a win, right?
I read that book!
Yuuup. Hey, look at this cool We Be Goblins adventure Paizo did for Free RPG Day. Why don't I run that? What's this? An adventure hook in the back of it for one of their Adventure Paths? Sure, I'll run that. Skip to five years later and I'm half-way through running another Adventure Path and I've done several other shorter adventures besides.
That said, I'm not the only member of our group that GMs, just the most reliable.
A party can definitely be too powerful for the narrative you want to tell. If you've got a specific story with specific challenges in mind, then players can have abilities that can render those challenges moot.
Using Pathfinder as an example, but this would apply to several related systems too: You have some kind of ravine or other traversal challenge. Prior to gaining access to fly, the players need to use their skills to find whatever solution you've seeded into the world or come up with some creative solution you haven't thought of yet. After gaining access to fly, they can simply fly across, nullifying the challenge.
All this is to say that in certain systems, it's not simply the numbers but the nature of challenges that change as you gain power. A high-level party tells different stories than low-level parties (this isn't an accident, it's a feature), and if that's not the kind of story the GM wants to tell, it can be a problem. Arguably, however, that's something the GM should have been aware of when going into a system like DnD or Pathfinder and been prepared to raise the stakes to entirely different kinds of challenges.
If your character's starting off at level one, they're really only getting started with adventuring. You can let that be reflected in their backstory.
If you want to play a badass, starting above level 1 is allowed, though probably not recommended for new players still learning the rules of whatever system you're playing.
As a 1e GM, I'd probably allow this, but I'd require you to take the Half-Dragon and Two-Headed templates and put you a few levels behind for it.
If it applies to DnD's cosmology, than it has to mean with viable offspring, because half-dwarves canonically exist in the Darksun setting and they're called Muls.