writing compilers is a fairly involved computer science topic, and while it does happen that some people without formal education in CS have written compilers,

writing compilers is a fairly involved computer science topic, and while it does happen that some people without formal education in CS have written compilers, I'd suggest that most compiler nerds are educated to at least undergrad level, more likely masters level in CS. So sure, neither of those are PhD's, but it seems odd to praise one aspect of formal CS - writing compilers, and not another - gaining a PhD.