Gathering intelligence and moving into their partners/supply chains territory is literally the DNA of Amazon. I know of no other company that does it as verociously as Amazon, who went after every partner that helped them grow (fulfilment, delivery, third party sellers, manufacturers).

And the example of Facebook with Onavo is also not plucked out of thin air[0].

Sure, it's not how all of the world works but for the big players, it's a important tool in their toolbox.

[0]: https://en.m.wikipedia.org/wiki/Onavo

Industrial espionage is a real thing, if you believe it or not.