So few people trained or specialized in language implementation and compiler writing actually get the chance to write compilers. Those jobs are just so rare that many people in that area re-specialize into something else (like AI these days).
It is a Chicken-or-Egg problem, as most commercial attempts at compilers were awful partially compliant bodges, and or expensive.
The GNU gcc groups win is rarely considered these days, but kids who were stuck with masm, risc asm, or Basic thought they were heroes to the hobby.
Slowly, the FOSS compilers grew in features, and commercial entities realized it was less risky to embrace an established compiler ecosystem, and paid people to port in an experienced user-base.
Starting from scratch is hard, as people often make the same logical mistakes. =3
"There are two mistakes one can make along the road to truth...not going all the way, and not starting."(Prince Gautama Siddhartha)
They aren't that rare. And AI is expanding the niche because making parallel linear algebra go zoom zoom is compiler work. There's also a lot of quantum compiler work.
Ya, I almost got a quantum compiler job at Alibaba (they decided to go in a different direction), and a job with Microsoft working complied ML support for Julia also fell through (I passed the interview, but they couldn’t get the head count) before ultimately joining Google working on developer experiences.
Then there are the people building compilers accidentally, like in the <xyz>-as-code space. Infrastructure automation deal with grammars, symbol tables, (hopefully) module systems, IRs, and so forth. Only the output is very different.
And of course the toolchain space is larger than just compilers. Someone needs to maintain the assemblers, linkers, debuggers, core runtime libraries. If you are building a Linux distribution, someone has to figure out how the low-level pieces fit together. It's not strictly a compiler engineering role, but it's quite close. Pure compiler engineering roles (such as maintaining a specific register allocator) might be quite rare.
It's a small field, but probably not that obscure. Despite the efficiency gains from open-source compilers, I don't think it's shrinking.
