What is your basis for this claim?
I am only aware of QNX as a commercial microkernel (and real-time OS) and that is widely used in cars, medical devices, etc. with a strong reputation for reliability.
But for many tasks, Linux is good enough and free, which is hard to beat. But that does not mean that Linus is automatically correct in his statements.
At the same time that Windows NT was being claimed as a microkernel, Linux was outperforming and had a reputation as being more reliable. Ditto with Mach. And GNU Hurd famously was hard to get running at all.
QNX is highly reliable, but is also a specialized use case.
I am of course including supercomputers, embedded hardware, and hand-held phones. Admittedly Windows has greater support for is running consumer hardware for desktops. But that has to do with how small the Linux marketshare is. And is hardly an indictment of Linus' work.