C and C++ still see overwhelming usage in many industries because of the business value they provide in terms of performance and how quickly you can produce software in it. That does not seem likely to change any time soon- game studios are not widely adopting rust, for example, and I don't expect that to change, even though they impact a MASSIVE amount of people.
Hare's value proposition is simplicity- which allows you to better reason about the software you write, for one thing. We are each entitled to our own opinion about how valuable that is.
C and C++ are at diametric opposite ends of the scale of value proposition. Listing them side by side eliminates any credibility your argument might have had.
Hare's "value proposition" of simplicity is, simply, a shuck. Any software effort has essential complexity that your language may help you manage, or chuck you in the deep water to sink or swim. Hare does the latter, and is even self-righteous about it.
I mentioned performance and game development specifically. I'm sure you're aware that it's common to write C++ that's very close to C while taking advantage of few features of C++. I don't think it's fair to call that the "diametric opposite of C".
Your opinion of Hare's view of simplicity is your opinion. Any software effort has some amount of essential complexity, in my experience many languages and tools quite a bit of incidental complexity that could be avoided.
You can write bad code in any language. (We used to say "you can write FORTRAN code in any language", back when.) C code compiled with a C++ compiler is C, and bad. With the C compiler, you had no choice. You do not get that excuse when you have a C++ compiler.
Avoiding unnecessary complexity is everybody's responsibility. Dumping every last bit of unavoidable complexity onto the programmer where it has been long demonstrated that tooling can take care of much of it is simply irresponsible, and inexcusable.
Hare's value proposition is simplicity- which allows you to better reason about the software you write, for one thing. We are each entitled to our own opinion about how valuable that is.