Not every thing is a "One of". many want small code to fit in a small chip. They want it done fast and cheap. as in lees bookable hours. If a well supported 1000 USD compiler does it, then use it.
For the big name compilers it is not that hard to find a consultant with it. The cost of using a hobby grade compiler may be eatten up in the extra time needed to finish the project, or the bigger chip it needs.

Maintainability? The programmers who take over your code someday will find out how maintainable it is.
Poorly written HLL code is hard to modify, like any poorly written code.
Well written ASM code may be hard to modify if the programmers style is totally different.