People will try all sorts of weird language experiments, so it's no surprise those libraries exist. But do you really expect a significant number of web developers to shift over to C, just because it's technically possible?
Micropython is not really python (which by definition is defined by PEP and CPython implementation), it's a language largely similar to python 3 since you can't just pick a python program or library and run on it at all times, but it's not really a relevant discussion (and it's nice to have multiple variants of a language you like that are good for multiple purposes, which solves the bloat problem as long as you use only one of them at a time).
Regardless, I hope Julia gets to the point that you can target as many places as some of those languages even if it's not nearly the best in each domain (like WASM, embedded, OS stuff, shared libraries).
I get your point, though.
https://www.micrium.com/rtos/tcpip/
Quoting the relevant quote "you wouldn't use C to write your simple website", except that is exacly what EE does when on device memory is measured in KB.
C++ would be safer, but the C89 culture reigns in such domains.
Even if we don't use technicalities, Julia is a very powerful language that allows people to extend it for purposes it was not built for. If it didn't support JSON, you could write a JSON type as integrated and fast as what the stdlib offers, it's metaprogramming/multiple dispatch paradigm allows for easily creating frameworks for many purposes and while numerical processing gets special attention the language will still outperform in terms of speed most dynamic languages in any domain.
And I do think short scripts are within Julia's main targets and are merely victims of the fact that the language is still too young and the battles the devs chose to fight within that limited time (and either AoT options or an interpreter that runs code while it's compiling could solve it really well for example, but both would require a lot of time and work which could be used for other features).