Weird, I explored the entirety of the Dreg Heap at my own pace and at no point I felt I was being "punished." The only places you're supposed to run through are where the angels are, and once you kill the first angel you can backtrack and keep exploring. You actually have to in order to meet Lapp for the first time. I'm not sure what you're on about.
Let's block out the entire area, since apparently that's going to be necessary.
You fall down to the first actual play area. The encounter is multiple summoner-type enemies that spawn a horde you're likely to get mobbed by. If you choose to fight the creatures immediately in front of you, you will get swarmed. If you recognize the summoner and charge them, you will likely get blindsided by the fact there were two more summoners that group-pulled with them, leaving you with a horde at your back herding you toward the ledge.
The ledge, by the way, which has a very obvious item on it. If you do the obvious thing, and run to the ledge to get the item, it breaks and drops you out of this encounter safely, which basically sets the tone for the entire zone. This is likely to be the experience of most players their first time through, either immediately or right after killing the first (most obvious, on the right) summoner.
You're dropped down into a room where you are immediately and completely surrounded by enemies that you most likely have figured out by this point are prone to swarming and blending in with the ash. The obvious answer for any reasonable player at this point is to GTFO; being surrounded is bad and fighting in terrain that favors the enemies is dumb. Most players will probably die here, and the ones that don't will mostly run out of the room to try and get somewhere they can better evaluate the situation from, since the items in the room are less obviously placed in terms of LOS on entrance.
If the player does go outside, they're presented with the first Angel encounter. The Angel is straightforward: you run like hell to cover or you die. There are only two available points of cover: back into the moshpit, or down a one-way drop further into the zone. Guess where most people are going to go?
At this point, enemies will still be spawning near the player due to the summoner, so they're likely to keep running. As soon as they enter the next room they're going to be presented with a pair of Lothric Knights getting their buffs on, which is something most players at this point (having been through Lothric Castle, presumably) would rather corral out to a point where they can take one-by-one or avoid entirely, especially if they're worried that the summoned spawn are still going to be popping up/following them (which is a sensible concern, considering they were clearly able to spawn outside of the room the summoners were in).
This is the first time in the zone the player is even slightly encouraged to interact with the environment, and even then, doing so is still relatively contra-indicated by the way they've been conditioned by the encounters up to this point. There's a doorway on the right that lets them opt out of the encounter for the time being, and they still haven't seen a bonfire yet. Most players will probably skip an avoidable encounter at this juncture and resolve to come back once they find a bonfire.
... and head right out into a spawn mosh pit, this time with the summoners hidden away behind illusory walls and thus a seemingly unlimited supply of enemies with a nebulous area that they threaten. Time to beat feet!
... right out into an open area, which we've already been taught by the Angel is not somewhere we want to be, so any reasonable player will by booking it. There's actually a reasonable encounter to fight here with the abhorrent fatty, but at this point we're probably so used to blitzing from the rest of the zone that we're not even going to bother.
Even once we hit the end and kill the Angel's conduit, there's no way back up through the zone on foot, and without any guarantee it won't respawn if we return to the previous bonfire (as there's no guarantee it wouldn't), our hypothetical player is probably just going to soldier on to the next zone.
... and guess what the first real encounter in that zone is? Yep, another Angel, which--although we
could reach the conduit and destroy it--we're likely to assume is being sourced from somewhere near the end of the zone, unreachable to us for now, a theory well-supported by the abundance of cover and comical "Thralls getting blasted" scripted event. Welp, guess we're back to running like hell, huh?
You see the problem? The design of your level encourages certain behaviors. The accumulation of those behaviors becomes a heuristic for solving the problems you present to them. If you continue to present similar problems that can be solved with similar solutions, they're most likely going to follow their established heuristics.
The behavior encouraged by the Dreg Heap is running, because problems are either
actually intractable in their current form or at least seem that way. This is surprisingly well-taught by the first time the zone throws anything at the player they
shouldn't be running away from, and then reinforced immediately in the next zone, even though it isn't the intended heuristic for problem-solving in Earthen Peak.
If it was intended to do anything other than get players to speedrun the zone, it's poorly designed.
