Role of else if (state == OUT) in C word count

I'm learning C following the book "The C Programming Language" - K&K; I found myself stuck in the understanding of the role of else if (state == OUT):

#define IN 1
#define OUT 0

main () 
{
    int c, nw, state; 
    
    state = OUT;
    nw = 0;
    while ((c = getchar()) != EOF) {
        if (c == ' ' || c == '\n' || c == '\t')
            state = OUT;
        else if (state == OUT) {
            state = IN;
            ++nw;
        }
    }
    printf ("%d", nw);
}

In the word counting program, I mean, in the way I read it there must be something I am doing wrong, because I fail to understand why this makes the difference, from simple else, since state = OUT is already default condition; but in practice I observe that it does, because if I write just else then the statement state = IN; ++nw will count characters and not words;

from the way I read it, the loop is saying that for each input character (stored in the variable c), if it is a space, a new line, or a tab, then it's value is zero, everything else, will be 1, so I fail to see how it is grouping characters into words, because state was OUT already before the loop, so how is else if (state == OUT) getting the program to put the characters into one word?

I have been thinking whole night about it but I couldn't find an answer in my thoughts, nor in the book