Yep. challenges where the party isn't going to be high enough level to have the resource to overcome the challenge (like a 4th level party needing a 3rd level spell), or must-win-to-proceed scenarios where the party has have the exact spell prepared and accessible with no hints to the party that they'd need it. I don't mind scenarios you can't win, but do I mind scenarios you can't win but have to in order to proceed with the quest, or have only one very specific way to overcome it that most party's won't be set up for. Especially in 5e, where it was designed to have multiple classes do multiple things, and not require class X with spell Y that only they could cast like in 1e.Having an area where the party must have access to a 3rd level spell to defeat a foe when they are only 3rd or 4th level - just stuff that the writers put in because they thought they were being clever - that's the stuff that gets a party killed (or otherwise leaves the entire group frustrated when they have to retreat and level grind). Frostmaiden does this on several occasions, puts up arbitrary roadblocks.