In designing System Shock and Thief: The Dark Project, Looking Glass Studios aimed to achieve a "role-playing" experience that was quite different from videogames that drew their mechanics directly from tabletop RPGs. A key insight was that much of the arithmetic that in a tabletop environment might burden players and DMs alike could, in a digital environment, be handled more or less exclusively by the computer. A certain minimum of numerical awareness on the player's part is still necessary (health, ammo, etc), but there is simply no need for the usual RPG rube goldberg machine of having to do things to cause some numbers to go up to get some other numbers to go up in order to get the numbers you actually want to go up to go up.... Far more elegant approaches to player progression are now possible, and what Looking Glass achieved with System Shock—progression based on collecting equipment and suit upgrades—converges onto territory analogous to what Jeremy Parish charts in the transition from the console action-RPG to the metroidvania.

True, SS2's leveling system (by another name) is not exactly the sadly familiar contraption described above, but there is still a diegetically nonsensical experience currency that muddies the intuition driving the equipment-based elegance of SS1. True, grinding is not possible, but like all RPGs even with grinding, the whole system progressively locks the player out of options as the game advances, which by a sleight of hand is disguised as "choice." It is expressive enough that I may choose which weapons to fill my limited inventory space with, attending to the limitations imposed by the available resources (ammo, energy, etc), without forcing me to put points into a skill tree to use them effectively, or at all.

I'm admittedly being perverse in framing the benefit of such systems as a disadvantage when it's really a tradeoff: these systems allow for distinct paths of player character growth which, to be meaningful, must be mutually exclusive. That's nice. I prefer it the other way. ¯\(ツ)/¯