This is extreme hyperbole.
The bulk of the relatively simple quests occur in the Hinterlands when they make most sense.
At that point the Inquisition is relatively young. At that point you are still an agent of the Inquisition who is gathering influence and power for your organization by any means necessary. It's relatively simple to know what quests have "content' as opposed to those that don't.
After the Hinterlands, each zone has only one or two true fetch quests that still have some context that allows degrees of roleplaying, like the two fetch quests in Exalted Plains that are given by a Gaspard and Celene soldier.
Even so, many people here completely undermine the importance those little fetch quests have on shaping the character of your Inquisitor. Sure, fulfilling a random woman's wish to release her son's ashes at the edge of the Emerald Graves may seem a trivial task, but it's still a task undertaken by your Inquisitor to realize a characteristic you have assigned for them.
In one playthrough, my Andrastian warrior did it out of respect for the Maker. In another, my elven mage pitied the woman despite not believing in the Maker. In a third, my dwarven rogue scoffed at the idea of doing this menial task and moved along.
They're even recognized by your characters. Incremental relationship changes as they see a side of your Inquisitor.
Honestly it feels that many people here who claim to want immersion don't even bother to do so, failing to even attempt to involve themselves in the quests as trivial as they seem.
You claim that the "bulk" of the quests are fetch quests. Ignoring the fact that everything can be classified as a fetch quest if you try hard enough, you'd see that this is not the case.
Most of your time spent in DAI is:
1) Exploring the areas
2) Developing relationships with your companions, advisors, and major NPCs via dialogue and action.
3) Completing the main missions of the zones (including the temple exploration)
4) Completing the main quest chain intermittently throughout the game.
5) Sealing rifts
6) Collecting materials for crafting / crafting and improving Skyhold
7) Completing trivial side content
It's arguable that 1) takes a significant portion of gameplay time. A lot of people here tout that they spend a lot of time doing "fetch quests" when what they're actually doing is traveling throughout the zones in order to complete them. There is literally almost no grinding in the game for completing those quests. They're simply there to guide you throughout the area as you complete the more plot-critical missions. If there are any "grindy" quests, they all occur in the Hinterlands.
Just take the Fallow Mire as an example. You have to find the missing soldiers. While doing that you can clear the marsh of undead by completing a VERY hard kill quest chain to purge the undead influences. You can find and defeat a renegade mage who wrecked havoc on the local populace. etc... You do all that WHILE exploring to find the missing soldiers.
A very significant amount of time is spent speaking to those you know. How much time do you go back to Haven/Skyhold to talk to your allies? How much time do you spend assisting them? True there are some "fetch quests" involved in attempting to make them like you, but those are purely meant to give a bump to your relationship. They take the role that "gifts" had in DAO, except they're far more nuanced and interesting. There is not much character-building by giving Alistair a runestone, but an Anti-Circle mage might take issue with helping Vivienne recover tomes for the Circle. Someone who despises running errands for people would not help Blackwall, etc..
Every zone you enter has a main mission to complete. You go to the Emerald Graves to cleanse the "cult" that is forming there. You go to the Exalted Plains to assist the soliders and that takes a LOT of your time, from clearing out the undead-infested barricades to saving Celene's soldiers from a trap-ridden Elven fort. The questlines in this area heavily relate to the ones in Emerald Graves, so there's some inter-zone story going on here.
Also in the Exalted Plains, you can either develop a symbiotic relationship with the Elven clan or you can go out of your way to **** them over in every shape or form from killing their sacred creatures, to plundering their structures in the name of loot, to giving the Chantry the true account of what happened at the Red Crossing.
The main quests speak for themselves.
Sealing rifts is the "primary" purpose of your Inquisitor. Complaining about doing those is similar to complaining about driving in a racing game. You're here to stop demons, so stop demons.
Crafting takes a major role in Inquisition, offering the character ways to develop their squad in an alternative way. This part is integrated with exploration since you normally collect materials while exploring. Still, you go out of of your way to acquire materials and schematics to upgrade your character and take an active hand in developing your character.
You can upgrade potions and grenades for various effects and purposes. Many times those upgrades are integrated into character development. Is it not better that they are separated?
While exploring, you can collect materials in order to craft those upgrades. Speaking as an RPG player, when I found the first "Crystal Grace" I was happy as hell and went back to Haven to get the upgrade for a potion I wanted.
Crafting gear acts as an alternate form to acquire upgrades for your character. You can develop them in any way you wish and create your own unique style.
Only after all this do I consider the time spent on fetch quests. Even the most basic of "fetch quests" from unlocking astrariums to collecting shards have relevance. The former gives you detailed codex entries regarding previously unknown lore and history, while the latter gives you character upgrades in a concentrated location to serve as some game-spanning mystery to solve. What's the deal with Solasan?
Is anyone going to claim that fetch quests took MOST of their gameplay time? They're lying. In fact I'd make the bold claim that the same people who call DAI a "fetch quest extravaganza" also dislike exploration and would prefer linear quest chains like in DAO.
That's fine, but DAI was marketed as an exploration-heavy game. As I said before in a previous post, this is how the game is. It's not a fault, so either deal with it since you bought it, or move on to another game that is more aligned to your interests.