The reason is very simple, the billions of wasted money fixing security exploits caused by industry's adoption of C.
Morris worm is more than 30 years old, and the old ways can still be used to attack modern systems that people insist in writing using C.
https://msrc-blog.microsoft.com/2019/06/14/prevent-the-impac...
https://support.apple.com/en-us/HT210348
https://msrc-blog.microsoft.com/2019/07/16/a-proactive-appro...
https://kernsec.org/wiki/index.php/Kernel_Self_Protection_Pr...
https://security.googleblog.com/2019/08/adopting-arm-memory-...