New OSes that have come out are pretty much universally microkernels. Fuchsia from Google is on a lot of their devices, and is a microkernel. SeL4 and QNX are microkernels for security and safety critical devices. I believe that Firecracker from AWS is also sort of microkernel-like (but pretends to be Linux). If you are building the device, the kernel, and the software, chances are that you are using a microkernel in 2024.
Windows and the Unix OSes just have a lot more market penetration, strong network effects, and a big first-mover advantage. That means that when you are buying your OS or your hardware or your software, you're probably stuck with a monokernel.
Lots and lots of home users care more about the few % of performance than the nebulous "extra security".
I have friends who use their desktop for gaming only, literally nothing else, I guarantee they don't care about the extra security a microkernel claims to offer.
Windows and the Unix OSes just have a lot more market penetration, strong network effects, and a big first-mover advantage. That means that when you are buying your OS or your hardware or your software, you're probably stuck with a monokernel.