On the topic of DLC and Sequels (in terms of gameplay)

I want to take some space here while everyone is enjoying Silksong to talk about the nuance of DLC and a Sequel in relation to gameplay depth / difficulty. As we are all kind of aware now, Silksong is hard. I'd peg it somewhere around mid Hollow Knight progression-wise and it escalates from there (some would say too quickly but I like the pace, personally).

First off, I don't want to complain about this. I will go on record to say that I like challenging content when it's designed well. I like what I've played so far of Silksong (roughly 5 hrs in). My favorite MV games are Rabi-ribi, Prince of Persia, and I also like stuff like Celeste and Star of Providence. My perspective is difficulty is good when done well, and I have the expectation that a sequel should challenge a player more than the original game if a core principle of the game is challenging content.

Which is to say that I like Silksong a lot, despite flaws with how the difficulty is mixed with aggressive fights, double mask damage, and the currency stuff. What is interesting though is that this is something that atleast started in part as DLC. Why is that interesting? Because I think when we think of game progression, there is a tendency with "hard" games to have the expectation that the DLC will be more challenging than the base game. In fact, I'd wager the majority of single-player games with DLC styled expansion content market that content as being something you are meant to engage with either after the story concludes, or some point after the halfway mark. Some examples - All the Souls game DLC, Minerva's Den, Delicious Last Course, Blood and Wine, Farewell in Celeste (free update but still), We look at good DLC as being full of harder bosses, more interesting movesets, level design that incorporates more mechanics, etc. Simply, the DLC has the expectation that the player has not only played the game, but is proficient with the base content.

On the contrary, sequels have the opposing sense that you start from square one again, or close enough. Metroidvanias may do this as a design constraint built by the system of non-linear upgrade exploration, but it's prevalent in other genres. The knowledge of the previous game may be useful, but the game itself is built on the grounds that you can start from here. Things like tutorializations, early easy levels, and a curated difficulty curve that starts closer to the beginning of the previous game create this sensation.

In a general sense, I feel DLC gets a pass as being meant to be an extension of the game's identity, which includes difficulty. DLC, no matter how long it takes to produce, exists still within the confines of a game and the gameplay systems are created then on this base foundation (exceptions do exist - Old Gods for Doom Eternal for example). Sequels, however, are more in a void state. They don't belong to another game so developers have to make a choice about if they want to cater to an audience who realistically could be exposed to their game as the first experience. Nothing stops you in the real world from reading Dune Messiah before Dune. You'll just be confused at times. Additionally, nothing stops you from playing Dark Souls 2 or even 3 before the first. You might miss some things but overall you'll have a better time than with the book example. And I feel that is intentional on the part of developers.

So with that, I'm curious about other people's takes. About difficulty and other ramping elements of systems in DLC versus a sequel. If it's true that Silksong started as an expansion and that initially affected this or if you disagree. There is also a point to be made that practically all of HK updates focused on harder challenges being added. Maybe the small dev team in a general sense could have just acclimated to that level of challenge from the get go when designing things over time. I read that there were very few playtesters too which also could contribute here.

Again, personally I like hard difficulty done well, but what does the community think is fair when a game develops a sequel? Especially when that game makes overcoming hard challenges a major part of its identity?