Like, are you shitting me? Why? After a while, I would do this to every NPC, every time. But, yeah, it's a bad design.
It makes for a deeply unique experience overall
Perhaps the one you’d most object to is the DS1 DLC, that people paid money for, lacking instructions for access. It involves killing a specific enemy and returning to a previous location.
At the time, people forked over cash and had to prowl the whole game playing spot the difference.
And the Consecrated Snowfield is only accessible if you find two parts of a hidden medallion, the first in a castle later in the game than the lift it operates. The second is hidden in a jar underneath a mountain. But you can't just smash the jar, you have to talk to the NPC inside the jar twice before you'll get the medallion.
The market rewards abstruse design.
Also, all you have to do in the Snowfield is to take a teleporter: that's not very secret, is it?
And even then, while an item may say "use it here", if it's been dozens of hours since you got it you may just straight up forget about it.
That said, I think that the target audience for the DLC was always people who thoroughly played through the game.
Same with the other games' DLC; for Bloodborne's you need to be yoinked by an invisible enemy while in posession of an item; while it's very possible people were accidentally yoinked on their first playthrough, they will forever know that the item is a trap and will avoid getting yoinked.
(unless the item in question explicitly said "get yoinked to go to DLC", I forgot)
FWIW, after you get one half of the medallion, get invaded by Gideon's lackey and then talk to Gideon, he will tell you to look for the Albinauric woman, so at least they give you this much.
All in all, I find the quests in the base game relatively straightforward, but anyone with any prior experience in their games will have an inkling that if they care about quests' results, you need to double-check with the wiki.
That's true, but it is strange that you get there and get early-game upgrade materials, like Smithing Stone 2, etc. It seems like they wanted to emphasize that the Scadutree Fragments are the important things for scaling, and not your Base Game level, but you already have to be pretty high level and upgraded to beat Mohg.
To some extent it's a design decision maybe. From makes games that are harsh and unforgiving, but not too harsh - you can mess up bits of quests but not end up unable to get an ending (afaik) which kind of matches the gameplay (harsh but not rage-quit inducing).
"Make the person repeat what they just told you" as a process is very immersion breaking.
The NPC / quest thing means that, unless you go online, you will need multiple playthroughs and exploration to get every quest done, OR you need to engage in a community - the quests and lore are often all discussed, disseminated, notes compared, theories crafted, etc in the community after the release of a new game.
Whether that's good or bad design I'll leave up to opinion, but it's interesting.
(personally I don't have the time to do multiple 100+ hour playthroughs so I followed guides online)