I mean, not everyone spent their decade on distributed computing. Some devs with a retrogrouch inclination kept writing single threaded code in native languages on a single node. Single core clock speed stagnated, but it was still worth buying new CPU's with more cores because they also had more cache, and all the extra cores are useful for running ~other peoples' bloated code.
I find that good multithreading can speed up parallelizable workloads by 5-10 times depending on CPU core count, if you don't have tight latency constraints (and even games with millisecond-level latency deadlines are multithreaded these days, though real-time code may look different than general code).
