I'm writing my comment, so me, based on observations over time.
> That has very little to do with real microkernels.
It doesn't matter if it's "real" or not. My point was that any selling point a microkernel can come up with can be grafted into a monolithic one.
So one of the usual selling points of a microkernel is that you can run a filesystem in userspace and eg, can allow an user to mount a network drive. Well, no need to switch kernels just for that since they added FUSE to Linux.
As an user I don't care if it's pure, I care that the job gets done.
> Not at all. The "modern" approach you are describing is many decades old and single systems are still extremely common.
Modern compared to the very old idea of the microkernel, I mean. I can see that the idea had a lot of appeal back in the era of rare, room sized computers. Keeping a single machine going is far less important in modern times, where most serious uses try their best to treat any single machine as disposable.
Says who?
> * Linux has microkernel-like functionalities like FUSE. You can do filesystems in userspace now.
That has very little to do with real microkernels.
> * The modern approach to High Availability is to have redundant hardware. A single machine being fault tolerant isn't that important anymore.
Not at all. The "modern" approach you are describing is many decades old and single systems are still extremely common.