Sure, I think we can agree that at Google scale the business interactions with me as a potential supplier are automated and soulless.
On the other hand there are several large supermarket chains where I live, and while I have a small artisinal cheese making hobby, so far my interactions with any of them to put it on their shelves have been equally soulless.
Perhaps in this context the issue is not monopoly, but rather that I have nothing of value to offer them.
I cannot tell you how much I despise this idea that a company can be too big to talk to their customers/partners/products.
If your relationship to a company is so worthless that they can't spend 5 minutes of an employee's day talking to you, then what value could they possibly be providing you?
In this situation it's not "google providing the site owner with value."
It's the site owner providing Google with value (that they want Google to pay for).
It's not incumbent for companies to interact with every person who thinks they _should_ be a supplier to said company. I get people cold calling me every day wanting to be my supplier. I absolutely ignore most of that.
In this case Google's algorithm did not ignore the potential supplier. It evaluated the site and sent a reply saying basically "thanks, but no thanks".
Now, I understand your gripe - an algorithm did this, not a human. But this has been the Google way since long before they were a fifth of this size. So it's not like a competitor changes Google's way of doing business.
And Google's way is not a secret. If you don't like it, then don't have a business relationship with them (as a supplier or customer.)
On the other hand there are several large supermarket chains where I live, and while I have a small artisinal cheese making hobby, so far my interactions with any of them to put it on their shelves have been equally soulless.
Perhaps in this context the issue is not monopoly, but rather that I have nothing of value to offer them.