The problem here is developer salaries. So long as developers are as expensive as they are the incentive will be to optimise for developer productivity over runtime efficiency.
It seems fairly reductive to dismiss the legitimate advantages of increased productivity. It's faster to iterate on ideas and products, we gain back time to focus on more complex concepts, and, more broadly, we further open up this field to more and more people. And those folks can then go on to invest in these kind of performance improvements.
Certainly there are some, but I think we passed the point of diminishing returns long long ago and we're now well into the territory of regression. I would argue that we are actually experiencing negative productivity increases from a lot of the abstractions we employ, because we've built up giant abstraction stacks where each new abstraction has new leaks to deal with and everything is much more complicated than it needs to be because of it.
[0] plenty of slow as fuck modern software doesn't handle it even close to 'flawlessly'
Come on now. Let's be honest here. The answer for >90% of projects is either a faster pace on new features, or to pocket the payroll savings. They'd never prioritize something that they've already determined can be ignored.