Is this a problem with Intel or with the OS scheduler? Haven't they had this kind of CPUs for a few years now, with this being touted as a reason to move from Win10 to 11?

It doesn't matter to the public's perception.

Right, it certainly doesn't.

But since we're on a technical forum where my initial comment's parent seems to argue this issue is Intel's fault, I think it's interesting to determine whether that's actually the case.

Of course, had Intel not released such a CPU, we wouldn't be having this conversation. But since they have released similar ones a few years ago now, is it still (only?) their fault?

OS scheduler is responsible; AMD/Intel work with Microsoft on the NT scheduler and likely contribute code on the Linux scheduler.

The recommended actions are built around the assumption optimal gaming performance is the only market segment to please. Of course, efficiency cores were never about pleasing that segment anyways - gamers want fewer huge cores, not lots of big cores or tons of efficient cores. That Windows gaming is slightly imperfect due to scheduling difficulties will not stop AMD, Intel, ARM, etc from continuing to use different sized cores on non-uniform interconnects if it means larger changes in perf/watt and perf/cost for that price.

In practice this is more of a problem for gaming news site headlines than users anyways. For all but the biggest enthusiast the uplift from going to a new system is usually so much they'd not notice it could be a couple percentage points better or that one game is still a bit hitchy. It's us ultra-nerds that care about the 1% lows between different top end CPUs, and we tend to be quickly convinced the problem is Microsoft's to solve for us when the scheduling problem hits ARM, AMD, and Intel based Windows devices equally.

Scheduling is the OS’s decision not the CPU’s.

Although Intel’s configurations are unhelpful to say the least: it’s hard to make good scheduling decisions when Intel sells a 2P, 8E, 2LE as a 12 cores to the user.

Normally "let me google it for you" is impolite on this site but I hope not in this case. Here we go:

"Intel Thread Director leverages machine learning to make intelligent decisions about how to utilize the different types of cores in a hybrid processor, leading to better overall performance and power efficiency."

Feel free to unsee it and ban me.

Disclaimer: I work in gamedev on engine and performance.

It is the OS fault as you say but consumers don't care who's fault it is only that it's broken