Other Action RPGs have shitty combat. The vast majority of them do. How many games have better 3d melee 3rd person combat than the Souls series? Not very many, and the few that exist are not in the action RPG category, except maybe severance blade of darkness which I heard people say was better than Dark Souls and Dark Messiah but I haven’t been arsed to play yet. Finding good melee combat is a hard thing to do in the first place.
Beyond that, Dark Souls (and the series in general) is like that Gesamtkunstwerk thing people like to talk about, and I’m not just saying that because Mr B Tongue said it, I’m saying it based on different principles for different reasons.
Souls doesn’t just have a combat system that works on totally flat terrain with one on one enemy encounters, it has a combat system that varies significantly based on the terrain and structures surrounding the player. It varies significantly based on the number and type of enemies fighting the player. And it uses these as an opportunity to create level designs where enemies ambush you, surround you, fight you in conditions that favor them more than you, like tight hallways or from the high or low ground, with ranged reinforcements, and more.
Souls has level designs that are branched and interconnected, yet have a clear progression, beginning and end. It makes use of the Z axis to thread levels back through themselves in a number ways. On a higher level, it has a nonlinear progression between the whole levels, in the case of dark souls it has a multithreaded design that folds back in on itself in a number of places, so you can reach nearly anything in the areas before sen’s fortress with a skip and a jump. That and they just flat-out let you go to places you didn’t really need to early on, like new londo and the catacombs. New Londo even linked into the valley of drakes which links into everywhere else. They have shortcuts in the levels which get unlocked over time to interconnect areas and make runbacks shorter. This creates both a challenge to explore the world, and to route different paths across it to grab the shit you need to get other stuff done, and I like that type of backtracking.
Each game has a ton of different weapons that make the game all different and the courtesy to add massively varied enemies as well. Even the hollow enemies can be devastating, even if they’re a bit weak at higher levels due to more damage resistance. They’re all made in a way where it’s tricky to avoid their attacks, not just caring about doing a ton of damage or having a ton of health.
Not to mention they capitalized on a really unique netplay scheme before anyone else could, and it had the fringe benefit of preventing people in the single player from taking a degenerate strategy and ruining the difficulty curve of the game for themselves.
The Souls games did a lot of things right, they were just each crippled by a few things they critically fucked up.