I didn't say "make no mistakes". I said "using its features unwisely". If you can't write software that manages shared mutable state, then don't do it. The world still needs lots of simpler programs.
It isn't like C has some "there be dragons" set of features that are hard to use. The source of exploitable memory safety issues is consistently just foundational language features.
There is a catch, however. Some languages will not allow you to take some shortcuts you know are safe unless you can prove them safe.