As Ankan said, acid has been a major player in the High Elven history as well as the whole culture after it was discovered.
I’ve been playing solely in Haelun’or for what a year and a half now and not a single time has it been used outside of its original purpose. To rid the realms of the impure.
I personally find it stupid for there to be even a need for specific lore. For it simply is and it always will. Lore gives it the possibility for non-high elves to make it, and it has always been exclusive to Haelun’or.
It literally is the same as any other execution method, but as Ankan said, it is just High Elven.
May I ask how a regular beheading, for example, provides “enjoyable” roleplay and character development for the victim? None.
But it does provide enjoyable roleplay and character development for every single one who is taking a part in witnessing the whole execution.
The same thing goes for acid.
“Pitting” as we call it, has always been an event and does not happen that often. But when it does, more or less the whole player base of Haelun’or is witnessing the trial and the pitting that follows it. Just as a regular, non-high elven execution.
Beheading or mostly any other execution method is simply vulgar, it lacks any High Elven properties and that is why acid is used. It’s clean and does not require any physical aggression from a High Elf towards an impure.