I built a compiler for a simpler language as part of my compilers course in a CS degree. It was a non-trivial exercise well beyond the majority of software applications. What open source libraries did you have in mind and what are you copying?

If you can truly write a C compiler in weeks then kudos to you. How many compilers have you written so far for how many languages?

I work for big tech and I would say a large % of developers are incapable of producing a working C compiler on any reasonable time scale, certainly not weeks, even with looking at open source. I'm sure they can download one and run it. Most developers today don't even know C or assembler. They don't know how to approach the C language spec. The top 5-10% of developers/engineers can do it but even for them it's non-trivial.

> It was a non-trivial exercise well beyond the majority of software applications

That depends on how you count. By number of programs that may well be right, but that's not what matters in terms of impact on the industry, as software value roughly corresponds to the number of people working on a particular piece of software (or lines of code, if you wish). By number of people/LOC most software is not in the "simpler than a C compiler" category.