From what I understand, increasing cache locality is orthogonal to how much RAM an app is using. It just lets the CPU get cache hits more often, so it only relates to throughout.
That might technically offload work to the CPU, but that's work the CPU is actually good at. We want to offload that.
In the case of Electron apps, they use a lot of RAM and that's not to spare the CPU
Pressure to optimize can more often imply just setting aside work to make the program be nearer to being limited by algorithmic bounds rather than doing what was quickest to implement and not caring about any of it. Having the same amount of time, replacing bloated abstractions with something more lightweight overall usually nets more memory gains than trying to tune something heavy to use less RAM at the expense of more CPU.
Ton of software out there where optimisation of both memory and cpu has been pushed to the side because development hours is more costly than a bit of extra resource usage.
Of course memory safety has a quality all its own.