This runs contrary to my experience.
1. Coming from C++, my productivity is x2-x3 in Rust, making Rust a middle point between C++ and Python (about x8 productivity). What's more, if we factor maintenance time in, the lower costs of maintenance of Rust code makes the multiplier tend to x10, which is equal or better than Python (whose maintenance costs are important).
2. I have a colleague coming from Python (so a very different background than my C++ background), and he doesn't "get lost in the complexity of Rust" but after some use of Rust makes pretty much the same conclusions as I do: initial coding slower than Python, but roughly equal when you factor in maintenance time. He now writes the quick tools that could be Python scripts in the past in Rust when we suspect that they won't be one-off scripts (which happens very often). We get ease of distribution (static binaries), portability (to Linux and Windows), and better performance out of it too.
Although this is a comparison with C++ and Python, not C, the reasons why are simple and apply equally so to C:
1. Easy access to a good ecosystem. Adding dependencies in C or C++ is a pain. Very easy to do in Rust, preventing the need of reinventing the wheel (squarely). C suffers even more from this, given its lack of standard library and data structures (everything is a linked list :-D)
2. Memory safety and lack of UB in safe Rust brings a definitive simplicity in coding, code review and debug.
3. Result-oriented APIs and generally expressive type system are what end-up bridging the gap with Python with time.
What Rust definitely has is a learning curve. It is not optimized for taking the language without deep diving into it, or learning it in a short time. IMO it is a reasonable trade-off, given that the experience past the learning curve is so good, and that many of the things that make the learning curve so steep are integral to that experience (exclusive borrows, trait system, ...).