The problem I see with this view is preassuming success
That should NEVER be a thing, increase the requirements for “keeping it up” even if your loot diversity increase marginally over time, the requirements for it should be more and more obvious and drastic
The key part to focus on it is not make it look/feel “cheap”, i.e. on-off (or have vs not-have) things…
For ex. “hitstun” can also be added to some type of melee/hard-hitting fitghters, BUT should only be implemented to a point where the player feels “right” i.e. not make the game feel almost/completely unresponsive due to those things. In LE for example the mechanic is so overexaggerrated so much to the point of making dodge completely mandatory. Now though better than completely not having it, that is a failure of a design IMO, not cause it adds something in the mix and thick of things, but rather cause the hitstun as a mechanic itself is an on-off thing that you either dodge it or not dodge it… However, adding Blesses/Curses to the mix should be a step in the right direction I’d say (or something along the lines of adding hazards and maybe even verticality)
Regardless, point being - never “inflate” existing parameters, just increase the numbers in diversity it so that player never feels like having them all and will always have to figure out how to “make up for” those that are missing… Make the player always feel like, oh man do I get X or continue with my Y and try to overcome by being more aware of an attack incoming, or do I sacrifice a not insignificant portion of my ofensive fire/power (say somewhere around 10-15%) in order to feel more safe
e.t.c.
The GOAL shouldn’t be reward, the GOAL should be the experience of overcomming yet another challenge the player thought they couldn’t do it… “Gear power” can grow to a certain point before it becomes feeling “cheap”, increasing requirements for awareness and diversity of threats make up for the “lack” of endgame, makes the player “circulate” options and try a one, then another, e.t.c. until “finally” figuring out some things but then another “requirement” is met such a (not enough potions of invis, not enough charges of mirror-image, or damn it not enough obstacles to funnel these s*ckers and fight them in a nicely-closed space, e.t.c.)
Figuring that out and forcing the player to take tougher choices/risks alongside with increase of parameters to take care of (without the ability to cover every single one of them) will help with the endgame without making it a simulator of farming. Long-story-short, the game must pose some chance of failure before things get out of control
It is the way it should be. It may not be how games work but it is how common sense, math, and logic works. The alternative is exponential growth, and we all know that’s the worst option of them already