> There is no point in freeing blocks at the end of a program

...unless you are trying to find memory leaks in your program. In that case it would be very helpful if the program, and the libraries it uses, were written to actively free all allocated memory.

> I think many GNU tools just never free any memory

It is absolutely true that some GNU software (including libraries like glib) allocate memory that they never intend to free. This causes leak analysis of programs that link with these libraries to be more painful than necessary.