Avoiding "root cause" thinking doesn't mean that there isn't something that can be found and fixed. The intent is to keep your mind open to the fact that these systems and the interaction of their components are phenomenally complex. There are many contributing factors to a loss, not just a single error.
Root cause analysis is harmful because it artificially limits your investigation to a predetermined "single" error or fault. Once the first or most salient error or fault is found (very commonly a human operator), the investigation stops because the "root cause" was found. Instead of stopping at the root cause, you keep digging in attempt to find all the possible contributing factors, no matter how big or small. You can prevent many future failures of the system, not just the same one, by learning about many places where your defenses and mitigations were weak.
NTSB reports are a great example of how useful this approach is. Instead of identifying a root cause, they list many contributing factors, all of which can be improved to raise the level of safety significantly rather the fixing a single root cause.
As a recent example, think of the Boeing 737 MAX. What was the "root cause"? Was it:
* A software bug in the MCAS system? * The removal of a redundant method for sensing angle of attack? * The decision to make the "AoA Disagree" light an optional upgrade? * Making substantially unstable changes to the existing airframe? * The desire for it be be "another 737 variant" for pilot classification? * The insufficient pilot training w.r.t. to the new MCAS system? * Organizational pressures to not lose the AA contract to Airbus? * Executive leadership that prioritized business over safety?
The answer is all of the above, and more! By identifying all of these past "a software bug in the MCAS system" we have the opportunity to fix many safety issues which could be contributing factors to future failures.
There is an even more in depth example of this in Chapter 5 of Nancy Leveson's book Engineering a Safer World. She spends over 60 pages describing the environment and circumstances that lead to a US Air Force F-15 shooting down a friendly US Army Black Hawk over northern Iraq in 1994.