This has nothing to do with Rabbi Yosef Mizrachi. He is merely letting you know what the Sefarim say about this. His style is very black and white which leaves little room for nuisance.
The Ben Ish Chai writes a story of a person suffering for a past Gilgul and concludes that we see that ?? ????? ????? is not only with your own generation, it is even with past generations.
The Arizal expanded on the concept of Gilgul and it became much more complex. There is a while network of relationships between Neshomos.
There are different questions to answer about suffering. Why it exists, why this person, what is gained, what causes it, why this time, and why these people. There are different answers to the different questions. Gilgul is but one answer. It is part of the picture. It is meant to be aware that it is not random not as an explanation to any particular case.