For compilers specifically, I think plenty of people would disagree.

It's not that it's exceedingly hard in C, but programming languages have evolved in the last millenium, and there are indeed language features that make writing compilers easier than it used to be

I have the most fun when I write x86 MASM assembly. It's a pretty simple language all in all, even with the macro system. Much simpler than C.

But a simple language doesn't always make it simple to write complex programs like compilers.

It is really remarkably sucky to process trees without algebraic datatypes and full pattern matching. Most of your options for that are ML progeny, and the rest are mostly Lisps with a pattern-matching macro. While it’s definitely possible to implement, say, unification in C, I wouldn’t want to—and I happen to actually like C.

Given the task is to bootstrap Rust, a Rust subset is a reasonable and pragmatic choice if not literally the only one (Mes, a Lisp, could also work and is already part of the bootstrappable ecosystem).

Sure, for you it isn't. It is for me. Especially if we're talking "working roughly as intended" programs.

Rust feels impossible to use until you "get" it. It eventually changes from fighting the borrow checker to a disbelief how you used to write programs without the assurances it gives.

And once you get past fighting the borrow checker it's a very productive language, with the standard containers and iterators you can get a lot done with high level code that looks more like Python than C.

Writing non-trivial programs is easier in Rust than in C, for people that are equally proficient in C as in Rust. Especially if you're allowed to use Cargo and the Rust crates ecosystem.

C isn't even in the same league as Rust when it comes to productivity – again, if you're equally proficient in Rust as in C.

You have to consider that those who write the Rust compiler are experts in Rust, but not necessarily experts in C. So even if writing programs in C may be simpler than in writing programs in Rust for some developers, the opposite is more likely in this case, even before we compare the merits of the respective languages.

Writing programs that compile is much easier in C. It lets me accidentally do all sorts of ill-advised things that the Rust compiler will correctly yell at me about.

I don't remember it being any easier to write C that passes through a static analyzer like Coverity etc. than it is to write Rust. Think of rustc like a built-in static analyzer that won't let you ignore it. Sometimes that means it's harder to sneak bad ideas past the compiler.

This is probably true if you assume it doesn't matter whether the program is correct.

Yes it is, why would anyone use it otherwise?