Excel中sumproduct功能的原理是什么？

This function can also calculate something like the result of sumifs if I put an array into the criteria argument: =sumproduct(sumifs(sumrange, criteria range, criteria)). It gives me the sum of the sum of all the criterion in the array. If I just do =sumifs(sumrange,criteria range, criteria) and the criterion is an array, then the result would be zero. I could only check the result by pressing F9 and it gives me the sum of each criteria separately. Why can sumproduct function add up all the separate values here?This function can also calculate something like