I don't think this is true. Microkernels are a collection of OS processes interacting to provide a rich interface to userland (file systems, networking stack, IPC, etc), while hypervisors don't intend to provide OS services at all. They're just a thin hardware abstraction layer so that multiple operating systems (microkernel or not) can be fooled into coexisting and maybe some very coarse resource management.
Like atoms vs. the solar system, they might look similar if you look from afar. It's certainly possible to cherry-pick theoretical similarities. For real-world work, though, they tend to be quite different.