I like this example.
With a trapdoor, you already know its function. Your roll is to utilise its function.
With the runes, you do not know their function. Your roll is to determine (importantly not to discover) their function.
Now if you are able to determine the function of the runes (via successful roll) you can in theory
Determine that the runes heal the party
Determine that the runes cremove a curse or condition
Determine that the runes provide safe sanctuary to the party
Determine that the runes quench the party's thirst or satiate the party's hunger
Determine that the runes reveal information about xyz
Determine that the runes illuminate the area
Determine that the runes provide resistance vs abc
Determine that the runes provide an escape route
...etc (all via a successful roll ofc)
I think what is helpful is if we could ascertain the limitation, if any, on the players' creativity on the level of power that may be imposed on the runes with a successful roll.
THIS is the benefit the posters above are reflecting on.
That is a good framing. I'll leave the MHRP case to others, to focus on D&D.
In formulating my example upthread, I had in mind a more complex example that I omitted at that time, which was to compare with Charisma (Persuasion). It's worth laying out that example now.
Player 1 "We have to remove the curse. I believe the priest here in Tilverton could be persuaded to do that."
Player 2 "At sunset I'll transform into that dreadful creature! Can I help?"
DM "You can easily locate the priest in her temple, but she won't be badgered by a group. She'll see one of you."
Player 1 "I've the best chance! I'm skilled in persuasion so...?"
DM "Okay, she is hesitant and it is a 3rd-level spell so Charisma (Persuasion) against a DC of 20."
DM (continuing) "But her deity has an antipathy to yours, so make that with disadvantage"
Player 1 (rolling) "13 on the lowest die plus 4 for Charisma and 3 from proficiency Persuasion, it takes all my skill to manage it"
DM "She stresses how limited her access to 3rd-level spells is, and questions whether there will not be more urgent purposes... the arguments grow long as the day wanes. Fortunately, before sunset, your arguments sway her."
Across D&D groups I have seen DMs grant anything from healing to sanctuary to information to escape routes as a result of Charisma (Persuasion) rolls. With NPCs, it is often the case that the group do not know what parts they may go on to play. A roll to influence can determine that. For example, the priest above could just as well have been persuaded to heal, provide sanctuary, quench thirst or satiate hunger, illuminate the area, etc.