The program in this blog post https://ldpreload.com/blog/stack-smashes-you corrupts memory despite being well-defined C. If you think that program should output what it actually does, I think you need to point to the line of the spec that allows it to behave that way.
Stack probing isn't the only option. Other options include fixed maximum sized stacks, architectures with separate stack and heap address spaces, etc.
Hmm… Stack overflow is certainly meant to be undefined behavior, because even if modern systems really ought to be able to catch it, there are many existing systems and implementations that do not or cannot – and the C standard is intended to be maximally compatible with old implementations, to the point of allowing compilers to only treat the first 63 characters of an identifier as significant, or set a limit of 4095 characters per source line, to name two of the more egregious entries under “environmental limits”.
However, you seem to be right that the program you linked is technically well-defined C, because the C11 spec doesn’t explicitly address stack usage. Not only does it not set a minimum requirement for the limits of local variable usage or function recursion, as far as I can tell, it doesn’t even acknowledge that such limits could exist! But if the program is well-defined, it ought to be able to execute to completion. Aborting the process, even cleanly, is no more acceptable than corrupting memory. Thus, a compliant implementation would have to have an infinite amount of memory. Since that’s a bit unreasonable to ask… it’s probably better to treat stack overflow as implicitly UB. The allowable level of stack usage could then be treated as implementation-defined.
Which is not to say that compilers shouldn’t try to handle stack overflow sanely. Stack probing was long overdue, and I’d love to see better support in mainstream compilers for static max-stack-usage analysis, among other things. It’s just that the C standard is probably not the right place to mandate such things, considering how conservative and compatibility-oriented it tends to be.
