But back to my assertion at the top. It made SC gamers literally unfairly better. Gryo aiming, effectively programmable macros, mode shifts, radial wheels, action layers, targeted mouse clicks, button toggles, sliders, regions, I can’t even remember it all from back before it got heavily neutered. It got out of control to the point where you could bypass “cheating” standards and macros in big online games, etc. You could simulate inputs.

I don't remember SC being singled out for that. Steam Input actually started providing third party support fast introducing it for the Sony DS4 in 2016 with all the same configurations possible, and expanding support to other controllers over the years. Now it supports 8bitdo too letting the extra buttons have unique keys mapped to it and supporting analog triggers with gyro, which until then Sony was one of the few non-discontinued controllers to have that support in Steam Input. https://www.pcgamer.com/steams-dualshock-4-support-is-now-in-beta/ Don't remember this period of the Steam Controller being a " deadly-unfair device for competitive gaming", since if it was it would have been more popular and caught on like Cronus and Xim as opposed to from its release to discontinuation being a niche device among enthusiasts while many complained because they expected it to be like a regular dual joystick controller. This thread itself and others on other sites seems to support that with people saying they tried it and didn't care for it, don't get the touchpads, and some not even knowing of gyro. I even had a conversation in this thread with someone who believes people who say the Steam Controller must be good are being contrarian, since they can't imagine how people could possibly consider it good over regular controllers.

What I remember is that aim assist got cranked up over the years to the point some mouse users started dropping it for gamepad, which led to complaints about rollers growing. And then more complaints happened about rollers as regular controller users in games like Apex used Steam Input to set up movement exploits in Apex through macros and moving while going through their inventory like mouse and keyboard users. Then rewasd with it offering recoil script. And that took a while to happen with Apex releasing in 2019, which by then SC was discontinued the same year. Rewasd was especially notorious because of not only the recoil script, but being able to map controller inputs to keyboard and mouse for people wanting to XIM on PC.

It failed because it offered too much customization. Really.

I also disagree on that too much customization was why it failed. Steam Deck has the same "too much customization." Difference is it has dual joysticks. Many people who picked up a Steam Controller just approached it like a dual joystick controller so were disappointed, and they didn't want a controller that needed setup. I've been using Steam Input many years and aside from UI changes people disagreed with, Steam Input has become much more advanced and feature rich as opposed to "neutered" as you say. Introduction of things like chords, being able to set up multiple gyro activator inputs, touchpad gestures like in Sony first party games, and mouse delta to name a few over the years.

I was happy with the Steam Controller because I didn't pick one up expecting it to offer an experience like my Xbox controller I was using on the PC at the time. I got one because I wanted the touchpad functions the Xbox didn't have and picked it up intending to map mouse to gyro and the touchpad. But, most people don't want that. They want a pick up and play controller, no setup, and just be like the dual joystick controllers they used and they didn't need Valve for a dual joystick controller either with xbox offering plug and play support with no setup with no need for Steam. And if they wanted accuracy they'd just pick up a mouse.

Even gyro is niche among all controllers, which speaks to how much people just want a Xbox experience of plugging in a controller, getting controller icons, and just playing and don't care for aiming without aim assist. They don't want to set up anything, and that is what having dual joysticks lets people do.