Imaro
Legend
...because a system with a functional encounter design system will give you a good idea of that. An encounter that is designed to be a minor skirmish for 1st level characters (say, "medium" difficulty in 5e) is going to be pretty boring for 10th level characters, even in 5th edition. The party will roflstomp it. An encounter designed to be a serious challenge for 20th level characters (a step beyond "deadly") will be instantly lethal. The problem is, in 5e, the CR system is so useless, you can get the same problems from encounters built for level 8 and 12!
My question is...Why is a head up fight the only option? I mean if the pllayers decide that's thew only course of action and it's always their go to... I guess there's a point to be made but... I think there's bigger problems if that's the only and always option.
In your example above... couldn't that high level party instead intimidate, bribe or otherwise negotiate the "minor skirmish" 1st level encounter into perhaps giving them information about the area, a new threat, become regular informants and so on for them as opposed to just slaughtering them?
Couldn't the low level party decide to run... negotiate, trick or numerous other things the 20th level encounter.
As for the problem with the 5e's CR system... they are upfront that it is a rough estimate and with bounded accuracy making things across levels still challenging I'm not sure their should be that big of a difference between 8th and 12th level opponent. On top of that the prevailing and constant complaint around 5e combat is that it is too easy... I don't often, if at all, hear stories of encounters being insta-kills that were designed with the CR system in mind. And yes I remember the ghoul encounter... but one instance is not the norm.
Now, of course, some trivial things are still worth doing because they have some other rationale behind them, but we don't really have good words in English for "this genuinely trivial, no-challenge task that still needs to be done because we care about something that requires that task." Mostly, I think, because it's assumed that if the trivial thing is worth doing, you'd have done it already.
I'd be more apt to say assuming something is trivial instead of giving your player's the choice to decide that is a mistake. If the players don't want to engage with something they won't... if they do, they will. I odn't look at it as my job to decide for them what should or shouldn't be trivial for them to do or interact with in the game.... I feel like if I did this I'd be railroading them... and that's not how I run my game.
Which...has nothing whatever to do with encounter building. This is a total non sequitur.
Which also has nothing to do with encounter building.
Encounter does not equal combat... that's the main issue with your entire outlook on this.
I don't understand how these things are at all comparable. Besides, it's not like 5e doesn't have magic item prices. It does! Yet the books exclaim the "magic item mart" just fine.
Uhm... in the core rulebooks? Where exactly?