Just to underline your point, Sekiro's NPCs behave in a much more obvious and linear way relative to From's other games, so it's clearly a game design decision and not a technical one.

Yeah, I’ve been playing these games since DS1 (currently on my umpteenth DS3 run as I recover from surgery). The quests never fail to make me laugh.

Especially in Elden Ring, it also contributes to the ludonarrative cohesion. Hyetta's quest (no spoilers!) isn't meant to be completed by everyone, her story is a foil to Melina's "default" questline that is mandatory for beating the game. Other characters (eg. Boc, Sellen, Selivus, Thops) also have quests that are easy to start but deliberately obfuscated towards the end.

The JRPG logic is annoying, but From uses it to beg important questions about the game world and the player. Fromsoft characters like Lautrec live in infamy for being so slippery and deliberately misleading.