I'm quoting myself.
So what would I do for a Fear Check? This:
DM: the corpse springs to life and begins to rise. Roll a Wisdom save.
Me: ugh. 8.
DM: you are startled and have the frightened condition for this turn. (Disadvantage in sight of ghoul, can't go near it). What do you do?
Me: I will back away from it and use my action to cast sanctuary, praying to the Gods it will leave me alone...
Vs
DM: the corpse springs to life and begins to rise. Roll a Wisdom save.
Me: ugh. 8.
DM: you are frightened. Roll a d6.
Me' ok, 4?
DM: you stumble backwards and fall, dropping your sword and the potion of healing you were going to administer. The vial shatters on the ground. You are prone and the ghoul has Advantage on all its attacks....
The first is the 5e fear rules. It's one turn where my actions are constricted but not negated. I could run, cast a defensive spell, flail wildly when it approaches, but I get that call.
The second is based on the 2e Domains of Dread fear results. I'm prone, disarmed, and lost a potion to the check. Further, I'm unable to act at all due to this. The dice have taken my reaction to the fear from me, and how I got to play it was decided for me. Further, the effects are far more severe, as I'm effectively losing a turn, I'm easier to hit, and I'm without a weapon AND down a potion.
If You think the complaint is just the first allowed me to take a defensive action rather then suffer multiple disabling conditions, you're partially right (I did pick one of the worst options on purpose) but the fact the first still gives me agency in showing my fear while the latter does it for me is the main issue. One trusts me to be afraid, the latter tells me how I'm acting while afraid.
Okay.
What happens, then, if it happens to be true that most people are not good at, or even genuinely incapable of or unwilling to be, consistently and appropriately expressing that fear?
Because this argument you've made looks perfectly identical to a defense of Prestige Classes, as implemented in 3.x: it's perfectly fine to have pure roleplay restrictions on powerful prestige class abilities, and refusing to design that way means you don't trust players to roleplay sincerely and appropriately. But we went through that era...and we saw that that was
exactly what happened. Some people abided by the rules, sure. The vast majority did not, and that is the reason why folks are so allergic to PrC concepts today. It isn't because the concept is inherently bad. It's that we
had rules that trusted players to consistently abide by thematic and behavior limitations...and they demonstrably did not,
far more often than they abided by them.
So, where does that put the status of these "just
trust people to do it right" arguments? We've legit actually seen that break down so badly that the community at large won't even
consider a mechanical structure that relied on it in the past, even in 5e, the edition supposedly all about doing exactly that thing.
As far as I'm concerned, this
at bare minimum shows that alone, the "just trust people to do it" argument doesn't hold water. You need more than that to land the objection. That doesn't mean it's just flat wrong all the time, I grant that it still has
some force. But it can't shoulder the burden (of proof?) on its own. Whether or not it makes sense logically, it breaks down in actual practice, historically demonstrated.
Or, since I know folks are
so eager to trot this out against anything they dislike: "just trust the player to do it right" is a white-room argument. It doesn't
reliably hold up in actual, observed practice. Special cases and minority proportions, sure, but not the general case.