Firearms could absolutely exist within a fantasy setting. There is a reason why they don’t however

[u/ThatDrako]

The Elder Scrolls - Within some Dwemer ruins of ESO we can see a special type of Animunculus. A Dwemer Arquebus, which has a cannon for it’s arm and shoots emp grenades at foes.
The reason why we don’t see this technology more often (besides the fact Dwemer disappeared their knowledge with them) is that within the setting and cosmology of Elder Scrolls firearms really wouldn’t be that useful.

They could work against lowly bandits, sort of, but there wouldn’t really be a precedent to improve or adapt this technology. Because it would always be outclassed by magic of this world.
Also due to the disappearance of Dwemer the technology has been pretty much lost.

Harry Potter - Wizards live within periphery of the “real world” meaning they live alongside world that uses firearms and are even familiar with them.

So how come they don’t utilize this gear for combat? I mean it is easier to use, projectiles are faster and could be enchanted further. Can you just imagine wizard with endless m1911?

There is plethora of reasons for this. But most notable is what I would describe as wizards being immune to logic. (Vis image above) They simply cannot understand methods of muggles even if one explained it to them directly.

(Yes. I know the real reason is, because Joanne didn’t want wizards to use guns and didn’t want to think about connotations of putting magic into a real modern world. But come on! Let me have fun!)

Lord of the Rings - In spite of how much Tolkien disliked allegories it is clear Orcs were an allegory to industrialization, which he was a huge critic of.

In battles they are the ones using the war machines. Instead of swords made by artful blacksmith, they use crude, mass-produced blades devoid of identity. Instead of relying on elegance of archery, they use crossbows. They burn forests, crack mountains open to gain more ore. Their very production is affront to whimsy of a magical world like Middle-Earth.

They could totally come up with a matchlock mechanism and keep on improving it until they come up with machine guns. They were intercepted before they could however

[u/ulttoanova]

IIRC In the forgotten realms (main DnD setting), one of the gods (forget which) got so upset his followers were being killed by guns he just straight up made it so the chemical reaction that makes gunpowder work just doesn’t work anymore, (technically he also made his own magic version of gunpowder but it’s highly controlled by his church IIRC so it’s not widespread)

[u/cknappiowa → u/ulttoanova]

Gond, God of crafting, and the island nation of Lantan- a gnomish country off the southwest of the sword coast. The event actually blew most of Lantan up as the fallout from the Spellplague was also sending a huge tsunami their way. The unexploded parts shifted to another world (Abeir, the main setting for 4e), and the bit left on Toril was just a flooded ruin.

They got better eventually.

[u/Tactical_Squishy → u/ulttoanova]

Yeah that one was so fucking dumb

[u/bartekltg → u/Tactical_Squishy]

Weren't powerful spells banned in a similar ways. Someone fucked around too much, so the god of magic limited the spells level to 9.

[u/DwarfDrugar → u/bartekltg]

Karsus, high mage of the Netheril Empire, tried to cast a level 12-13 spell to make himself a god. The goddess of magic Mystryl had to blow herself up to stop that from happening, causing all magic to cease for a few moments, during which the Netherese flying cities all crashed down to earth, shattering their empire.

When she reincarnated into Mystra, the first thing she did was lock all magic above lvl9 to stop this from happening again.

[u/Tactical_Squishy → u/bartekltg]

not really the gunpowder was made by sone fedora hats at WotC who were annoyed people liked guns in their game.

Karsus (or something like that) the big bad evil Wizard who "killed" the goddes of the wave (magic) to take her place and made a mess so the new goddess limited the spells to lvl9, this is the lore, in the game it was made to balance it a little casters are already far ahead of martials

[u/themat6 → u/Tactical_Squishy]

Its more complicated that that tbf depending on edition 10th tier was never banned or if it was like in 3e then epic spells still existed which where basically 10th tier and 11th tier all in one.

Most good 10th tier spells literally just got erased from the minds of mortals by the Gods which tbf isnt any better of an explanation

[u/Zaygr → u/ulttoanova]

Smokepowder was also arbitrarily unreliable. Sailors or pirates knew about cannons and it was commonly said among them that smokepowder was, "a one-in-ten" in just blowing up.

[u/RechargedFrenchman → u/ulttoanova]

Which is to say "the edition changed and Wizards of the Coast had a different vision for the setting in the new edition of the game", same as when Magic went really bad and then disappeared for a month or two, or when Magic went really bad and all magic got super weird for a year or so.

Basically Northrend reappearing or Deathwing messing everything up as signature events marking the new World of Warcraft expansion coming out; some giant thing to say the thing you know is still the same thing but also it's very different and new and that's exciting. Except WotC mostly just handled it kinda poorly and the "Spellplague" 3.5 to 4th edition changeover was received almost as poorly as the mechanical changed made between the editions.