Why should I not be allowed to allocate a buffer that has like 10 or 20 extra characters of space and use a format string with %d in it? Why does sprintf have t

Why should I not be allowed to allocate a buffer that has like 10 or 20 extra characters of space and use a format string with %d in it? Why does sprintf have to be banned? But banning gets is obvious because it is by definition facing external input