The solution then is to fix that problem through mandatory reporting and unions, not to break up the company.
"Why on earth should an online retailer, a cloud computing company, a smart speaker company, an organic supermarket company, and a video production company all be conglomerated into one corporate entity controlled by one person?"
Because they built it. Do we tell people building startups that the sky is the limit, unless you become too big or do something too many people consider wrong, and in that case we'll take it away from you?
Also because an economy of scale helps consumers. Amazon Prime gives access to music, books, delivery of home goods, delivery of groceries, and much more. Break it up and you will have Prime Music, Prime Books, Prime Home, Prime Market subscriptions, each for nearly the same price - one sub for each piece you break the company into.
I agree something must be done - the stories of the workers read like Bram Stoker award-winning horror novels, but swinging the needle the other way and completely breaking the company apart is over-reaction.
My suggestion: mandate unions in every field, every worker must be part of at least one union, and union dues must be paid as a tax by the employers.