Historically I think the people that first ran into these issues and started talking about this was gamedevelopers even if it flew under the radar for many others since it was an era of less third party engines and code sharing.

The motivation was partially to solve processing on PS3's, the 7 usable Cell units have small memories of 256kb each so processing had to be moved to a compact/streamable memory format but developers were also concurrently fighting larger cache latencies caused by Entity Component hierarchies that had arisen as a solution to problems with inheritance using dislocated object hierarchies (ie separated linked objects).

Out of this grew the Data Oriented Design paradigm (that's intrinsically built on mechanical sympathy) that suited both Cell like streaming as well as minimizing cache effects for main-memory code where Entity Component Systems were reorganized to use cache efficient array processing instead of linked objects.

https://gamesfromwithin.com/data-oriented-design

Was the outside world oblivious? I'd say so to a large part, CPU's had gotten faster, more cores and memory latencies were masked to a certain degree for other kinds of code!

The Java people even pushed out their biggest mistake just as these effects started to become visible, the erased objects for generics that kind of locked in a design that requires generic list types to have disaggregated storage due to separate objects. In hindsight, this is IMHO the single biggest benefit that C# got over Java as their paths diverged as generic struct List<> object's have radically more efficent storage in C# compared to a Java ArrayList<>.

Afaik Project Valhalla still hasn't become mainstream even after almost _12_ years at this point, had they gone with proper generics at day one it would've been a trivial compiler upgrade.