But it does have to be said that there's little excuse for not doing it anymore for heavy applications, especially games. The tools/frameworks/engines have vastly improved, and people know (at least roughly) ahead of time what work is going to slog the CPU, especially in the case of a AAA studio.
Note: I'm only referring to relatively modern games here - anything that's older than when multithread really took off gets an automatic pass - it's not reasonable to expect someone to cater for a situation that doesn't exist yet.
there's little excuse for not doing it anymore for heavy applications, especially games
.... Wut. You chose one of the best examples of where multi-threaded workloads are extremely difficult and often impractical as your example of where it should definitely be used...? 🤦
Games are where it's the most difficult, nevermind enterprise workloads that can be multi-threaded on paper, while games can often not even make that work in theory. Game workloads are incredibly, almost insurmountably, difficult to multi-threaded for most teams and studios.
Not just from a technical standpoint but from a practical standpoint as well as you are significantly increasing the surface area for software defects, full of pitfalls and gotchas. Sure you can multi-thread your workload but now it actually runs slower than it would have if you never did this at all due to increased resource usage as a result of synchronization...etc
Games like factorio are rarities, where the developers had both a small game and scope, and all the time and resources they needed to produce multi-threaded solutions to their workloads. Engines like unity have ECS, which has limitations of use and comes with extra asterisks. But outside that and a few other examples actual multi-threading is a massive undertakings that may actually mean your Game cannot be delivered.
Difficult, yes. Impractical? Absolutely not, at least with some planning ahead. It's not trivial (and I never said it was) but it's getting both easier and more important every year.
Multithreading in games is much more difficult because you not only have to make sure, everything is synchronized, but also that everything finishes in time. It's a bit like a RTOS in that regard. Using a known and fixed amount of threads can be a sane choice.
Not much of a game developer myself- but, yea, I understand the challenges of multithreading, especially around the main loop.
If you want to learn something interesting, check out a few videos on the PS2 architecture, and the challenges around optimizing games for it. Its, very interesting.
I know your pain. Although, my gaming PC is only rocking a Ryzen 7 5800x. Not, nearly as many threads... but, there are a ton of games which are only using a small fraction of the available CPU.
If I recall, Assassins' creed was pretty bad about it.... Minecraft (Especially modded) was horribly single threaded. And- more.