Every setting doesn't need gunpowder, but to me the idea that gunpowder makes something feel not fantasy is really weird. Like have people not heard of Warhammer Fantasy?
Or the Wheel of Time, so yeah, pretty much this. It's a
good thing that many settings don't have gunpowder, but it's a problem if no settings are
allowed to have gunpowder.
Some of it, I think, may come from a place of desiring representation. For someone who feels gunpowder reduces the fantastical feel of a setting, featuring it makes them feel somehow excluded, while avoiding it doesn't feel (notably,
to them) like it's excluding folks who like both that and other things. But when you take this principle from guiding a single setting's construction and turn it into a
pattern, it becomes, "Because a contingent of people don't like gunpowder, no one is allowed to have gunpowder."
It's a bit like choosing to have a female main character, or a gay main character, or other similar things, in a video game or film. Folks who are used to always having tons of representation will feel a sudden and unfamiliar disaffection, and thus avoid or even boycott it...but they have no problem expecting everyone else to be perfectly okay with not being represented.
I'm reminded of a conversation I had a while back with someone, about someone they knew who had a genuinely understandable issue with a particular character in a video game being revealed as gay (or, at least, bisexual and formerly in a relationship with another man.) Specifically, this was Soldier: 76 from Overwatch. The person posting the comment didn't personally care--but his grandfather had gotten invested in Overwatch in part because S76 made him feel included, represented, in a way video games (and most entertainment media) doesn't do. It's rare to the point of nearly unknown to have a core, important, respected character who is clearly around retirement age, apparently 58. Presenting the character as gay/bi, however, alienated him from that representation, and even though I myself am not straight, I empathize and sympathize with him for feeling alienated like that.
All of this is to say, tech or non-tech, gunpowder or non-gunpowder, whatever we might consider, they all need to be presented for what they are: worldbuilding tools. That's why I so strongly push for, as an example, spending (say) 2-4 pages of the DMG talking about deities, different ways they can interact (or not!) with the world, and how these choices can affect the feel and story of a campaign, preferably with a couple of examples. Same for tech level, class/race availability, world geography (e.g. standard continents, islands like Iomandra, dry worlds like Dark Sun, etc.), overall tone (e.g. dark stuff like slavery/sexism/bigotry, settings mostly at war vs loosely at peace, the prevalence of magic, etc.), and similar topics. That should easily round out a 20-30 page chapter, not telling people WHAT to make, but showing them HOW to make a setting, and what knock-on consequences and effects their choices are likely to have.
IMO, the presence of such a chapter in a DMG would immediately elevate it to one of the better ones yet written. If it is but one such chapter of tools, guidance, and demonstration, it would almost surely deserve pride of place next to the most beloved D&D manuals ever written.
