It's googles game and they can play it however they want. I choose to no longer play on their playground, I am free to get my customers from wherever I want.
You are quite correct. Any of us could do that. All of us SHOULD be doing that.
In fact, organic search should be the SMALLEST channel in our revenue stream, as it is the one we have the LEAST control over.
Unfortunately, there are many businesses (probably mine included) that have something of a wonky business model and lack a clear value proposition. For those businesses, their main competency was the ability to rank high in organic search. Hence, they became overly reliant upon google.
So while some people are quick to curse google, they are slow to acknowledge that their main competence (the ability to rank well in organic search) would never have allowed them to make the kinds of money they previously made without google's help.
Now that their main competence seems to be losing any advantage, and their business model is unable to sustain them via other advertising and marketing means, they are adamant about pointing fingers at google.
Personally, I am looking to reinvent our business model.