The Eberron setting also has another thing that sets it apart from other setting. Manifest Zones. From the Eberron Wiki:
Manifest zones are certain locations on the world of Eberron that share a particularly close connection with one of the thirteen planes that orbit Eberron within the astral...
Back in 3e, the waxing and waning of Eberron's 13 moons heightened or diminished whatever magic each moon was associated with. And each of the moons was tied to one of the planes in Eberron's cosmology. When Fernia (which was tied to the Elemental Plane of Fire) waxed or waned, fire spells...
What about the reverse? The setting defining the mechanics. Dark Sun, Planescape and Eberron have it where magic operates a tad differently than it does in the Forgotten Realms.
And the designers were influenced by the untold millions of D&D fans who wanted certain things from past editions kept in the new edition. Which is probably one reason (out of many) for why certain things are the same in almost every D&D edition.
Imagine if this wasn't the case with any of the D&D settings. A Dwarf from Greyhawk would have lore and species features that would set them apart from a Dwarf in the Forgotten Realms. The elves wouldn't be identical because like the Dwarves, their lore and species features would be different...
Back when my party was playing Baldur's Gate: Descent into Avernus, my DM designed his own % Wild Magic table for the party's Wild Magic Sorcerer. Every time our Wild Magic Sorcerer experienced a Wild Magic surge, we 'dreaded' what was about to happen next. Sometimes the Wild Magic surge...
The question is by how much and which aspect of the setting gets defined by the mechanics. AFAIK, magic use in 3e D&D was one aspect that got defined by the mechanics. Not sure if it is the same story in 5e. For instance, back in 3e, the casting of certain types of spells were heightened...
Time for a smell test. :p We're going to have a member of each of the PHB species for you to take a whiff of their morning breath. :p
Aasimar- "Hmm...not bad, do I detect some heavenly notes in your morning breath?"
Actually, all Dragonborn have two breath weapons. One does some kind of energy damage; the other is morning breath which can be cured with a wintergreen breath mint. :p The latter requires a CON save, but only when you are next to one.
To me, one of the general trends in this thread appeared to be to make the Dragonborn more common. Like they apparently were in 4e's Points of Light setting with the Dragonborn Empire of Arkhosia.
@Maxperson was replying to a comment you said earlier about how some of us are role-playing a Dragonborn like we would a human, out of ease and ignorance. Your post here appears to be in response to a mini debate between him and @Epic Meepo. Two completely different things.
Exactly. Thereby becoming one in our mind's eye. whenever we sit down together with our friends in RL or VR. Eventually we might be do it like the characters in Ready Player One did it. ;)
Unfortunately, there is no real way to know how an actual Dragonborn thinks and behaves compared to a human. Each player who plays as a Dragonborn can only do their best at portraying them. And no two players will role-play a Dragonborn in quite the same way.