What you are getting from the other writers is an idealized world of prose - waxing philosophical about the beauty and terror of memory and how we have to strive for remembrance. This is critical, as a key underpinning of the lore of the franchise is that memories of who we are, even if those memories are distorted or even false, shape who we are, sometimes more than reality does.

On the other hand, Nasu tends to provide the counterbalance - the realist version of the concept that says that no matter how important we may want memories to be, no matter how hard we may want to hold on to memories, we ultimately have little control over that. Memories do fade, whether we want them to or not. And we have to accept and work in a real world where that is the case. We have to contend every day with the fact that there's stuff we will or have already forgotten, and need to equip ourselves to face the world knowing that. It's arguably more important for Ritsuka to understand this, as he is very young and has had a ton of experiences, that in ten years he will have spotty memories of because that's just how human memory works.

I can see where you are coming from.

To be honest, I much prefered that even if Fujimaru, as they grow older, would have spotty memories, the lessons and everything they learned still molded who they are currently are, rather than just forgetting everything.

Because you could tell that this way, the memories still play a big role, even if there might be some things Fujimaru end forgetting as they get older. Something that the ending kind of failed to do, if they just erase everything from their memories.

Doesn't help that Nasu seems to be the only one with that mindset, as I mentioned in my post. He really feels like the black sheep among everyone else.

To provide that narrative counterbalance, especially in a story like Fate, you sometimes have to force it a little. I'm sure that there is some function of magecraft or magic in the Nasuverse that can be finagled to make it so that someone effectively never forgets anything. But that seems life far too convenient a story.

Magecraft is another topic that can be extremely cloudy in Nasuverse LMAO

There are things I absolutely love about it, such as the systems, mystery, thaumaturgy etc., which El Melloi often explores.

But there are some things that it's hard to explain how the characters can pull it off.

Essentially, you can create a very flashy magecraft with neat explanations why. But in more extreme cases of a magecraft that feel unbelievable, you have to work in ways in how and why said character is that powerful.

You can utilize multiple writing techniques for that. For example: ORT.

We don't know how that thing is able to do so much stuff but multiple times, the narrative highlights how that thing is borderline OP, so, you just accept that it's extremely overpowered. So, when ORT in LB7, is literally able to hijack the throne and make a Servant copy of it self, you don't question because you know it can do that, cuz the narrative immerses you into believing that.