The size of current-day companies

I've been on an organizing spree the last few days, and therefore I'm setting metadata on many books. One of the entries is of course "Publisher."

I have decided to enter the publisher that is mentioned in the eBook.*

Doing this I've noticed that some companies have become a bit... huge.

Publisher: Del Rey.
Which is owned by: Ballantine.
Which is owned by: Random House
Which is owned by: The Penguin Random House Group
Which is owned by: Bertelsmann SE & Co. KGaA

Of course, Bertelsmann has other parts besides Penguin Random House, and Penguin Random House Group obviously has both Random House and Penguin as publishing houses, who both have branches like Ballantine, who each have publishers like Del Rey...

Isn't that a bit excessive? Is a company such as Bertelsmann (and News Corp, as well), too big? To be honest, I have a feeling that in the end, nothing good can come of it. That's just too massive to be one company, with too much influence. There are of course companies like that outside the world of media; in electronics, or medicine; basically everything, in the end, seems to conglomerate into 1-3 huge companies.

*