It is certainly not laughable to me. You have singled out Quicksort as the sole example of performance gains whereas I have used it as a single isolated example of very large performance gains that can be had. SIMD instructions have seen a lot of other mainstream use cases recently which also includes the memory copying or memcpy(3) optimisations amongst others. Your browser has a Javascript engine, and since it a Javascript engine, it has a garbage collector. Garbage collectors move memory blocks around all the time, and a SIMD optimised memcpy will yield substantial performance gains. Or faster JSON processing. Therefore, SIMD + an improved fab process will result in much larger overall performance gains for you and me as browser users as opposed to an improved fab process alone. It is also a realistic example of the «whole system performance» improvements if the browser is treated as a «whole system».
And an optimised QuickSort can also come in handy if one pokes around a large browser history or uses it as a knowledge base, which I do and use it on a regular basis. My browser keeps a uninterrupted record of all visited websites over the last 15+ years and being able to zoom in on a particular time span to find something within that temporal range quickly is important to me. I am almost certain that a sorting of sorts is involved somewhere behind the scenes.
Forget Quicksort. What percentage of your CPU time is spent running SIMD-optimized implementations of anything? And what percent of those are upgraded to new SIMD instructions each year? And what real world percentage gains are they getting considering other constraints like memory bandwidth, power, etc? The answers to these questions, multiplied together, put a very small upper bound on the overall benefit of new instructions per year.
I share your concern about new SIMD instructions not being used. It seems to me we're at an inflection point, though. ISAs such as RISC-V and SVE will enable (properly written) software to benefit from future wider vectors without even recompiling. github.com/google/highway (disclosure: I am the main author) lets you write your code only once, and target newer instructions whenever they are available, with transparent fallback to other codepaths for CPUs.
Given the various physical realities including power efficiency, I believe there will be considerably more SIMD usage within the next few years.
And an optimised QuickSort can also come in handy if one pokes around a large browser history or uses it as a knowledge base, which I do and use it on a regular basis. My browser keeps a uninterrupted record of all visited websites over the last 15+ years and being able to zoom in on a particular time span to find something within that temporal range quickly is important to me. I am almost certain that a sorting of sorts is involved somewhere behind the scenes.