I've not used MicroPython, but its fork, CircuitPython. My impression is that it's essentially a Python that doesn't interact with an operating system. Thus if there's a reason for a server to have an OS and interact with it, the regular Python would be preferable.

I also don't know how much of the more advanced optimizations of Python are built into MicroPython. There's always a dilemma between making it performant, and making it micro.