The quote you replied to is used to educate a reader how to understand an existing system. For example, it helps one understand why a system is in a state when as you say 'there's not necessarily anyone who wants' it that way. Rivers are polluted because there are some factors in the system which enable it.

Also, as the video I linked in the previous comment says: 'our first instinct is to blame people in the system and that is a low leverage response...actions people take are possible, feasible, and rational because of the universe in which they exist.'

I am not sure if you've read the book. But even though you've not used terms like feedback loops, etc. I think what you are saying is not much different from what the book says.

If interested, a chapter wise summary of Thinking In Systems https://www.youtube.com/playlist?list=PLL6RiAl2WHXEU04zFYyWr...