Nonsense. Adding more keywords to a language is avoidable? Or making the compiler stricter in checking the integral promotions is avoidable? Sure, it is, but only if you stick compiling all of your code with C89. You're barking at the wrong door.
Adding keywords can be done compatibly. Again, I'm not making things up. A C18 compiler can absolutely build K&R C programs that are probably older than your parents. (C23 did roll back some stuff, to much gnashing of teeth, and seems unlikely to become a default mode for that reason. Most projects are holding at C99/C11.)
