> However, in the specific context of stand-alone or freestanding programs, the "void main()" definition would be absolutely nonconsequential

One possible consequence I can think of: If your program is safety-critical (or even otherwise) you might be interested in running static analysis or verification tools on it. These tools implement the C standard, so they would emit a diagnostic on the use of void main.

Other than that, sure, the language police will not come and break down your door. If your compiler's docs say that it accepts this construct with the meaning you want, it is indeed an inconsequential, though also completely unnecessary, deviation from the standard.

For a freestanding implementation, the program entry point is entirely implementation-defined. It may or may not be called "main". In that kind of environment, "void main()" (or, better, "void main(void)") might be correct. You need to read the implementation's documentation.

For hosted implementations, "void main()" might be valid, but "int main(void)" is always valid.

A tutorial should not suggest "void main()" without mentioning any of this.

Reference: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf sections 5.1.2.1 (freestanding environments) and 5.1.2.2.1 (hosted environments).