Basic summary is that once you start getting more than a handful of feedback loops, the author through many examples cautions that maps of the system becomes more like physical maps—necessarily oversimplified. When you have four feedback loops under the right control of management, it's still a diagnostic aid, but you add everything in the US healthcare system, say—fuggetaboudit! And because differences at the small scale add up for long term outcomes, the map doesn't let you forecast the long term, it doesn't let you predict what to optimize, in fact, the only value that the author finds in a systems map for a sufficiently complex system, is as a rhetorical prop to show people why we need to reinvent the whole system. The author thinks this works very well, but only if the new system is grown organically, as it were, rather than imposed structurally.
The first criticism is, this complaint about being unable to change a system, is actually too amorphous and wibbly wobbly to stand. Here's what I mean: the author gives the example of the ICBM project in US military contracting as a success of the "reinvent method", but if you try to poke at that belief, it doesn't "push back" at you. Did we invent a whole new government to solve the ICBM project? I mean we invented other layers of bureaucracy—but they were embedded in the existing government and its bureaucracy. What actually happened was, a complex system existed that contained two subsystems that were, while not entirely decoupled, still operating with substantial independence. Somewhere up the chain, they both folded into the same bureaucracy with the same president, but that bureaucracy minimized a lot of its usual red tape.
This is actually the conceit of Theory of Constraints folks, although I don't usually see them being bold about it. The claim is that all of those hacks that you do in order to ship something? “Colleague gave me a 400 line diff, eh fuckitapprove, we'll do it live” ... that sort of thing? Actually, say ToC folks, that is your system running well, not poorly. The complex system is being pinned to an achievable output goal and it is being allowed to reorganize itself to achieve that goal. This is ultimately the point of the whole ToC ‘finding the bottlenecks’ jargon. “But the safeties are off and someone will get hurt,” you say. And they say somewhat unhelpfully, “That’s for the system to deal with.” Yes, the old configuration had these mechanisms to keep things safe, but you need a new system with new mechanisms. And that's precisely what you see in these new examples, there actually is top-down systems engineering, but around how do we maintain our quality standards, how do we keep the system accountable.
If the first criticism is that the “organically grow a new system to take its place” is airy-fairy, the second criticism is just that the hopelessness is unnecessarily pessimistic. Yes, complex systems with lots of feedback loops do maintain a homeostasis and revert back to that as you poke and prod them. Yes, it is really frustrating how to change one thing, you must change everything. Yes, it is doubly frustrating that systems that nominally are about providing and promoting X, turn out to provide and promote Y while actually being X-neutral (think for instance about anything which you do which ultimately just allows your manager to cover their ass, say—it is never described as a CYA, just acknowledged silently that way in hallway conversation).
But, we know complex systems that find new homeostatic equilibriums. You, reading this, probably know someone (maybe a friend, maybe a friend of a friend) who kicked drugs. You also know somebody who managed to “lose the weight and keep it off.” You know a player who became a family man, and you yourself remember instances where you were a dumb kid reliving the same shitty day over and over when you could have just done this one damn thing differently—you know it now!—and your days would have gotten steadily better and better rather than the same old rut. So you know that these inscrutably complex things do change. Sometimes it's pinning the result, like someone who drops the pounds because “I just resolved to live like my friend Derek, he agreed to take me a week through everything in his life, I wrote down what he eats for breakfast, when he hits the gym, how much does he talk with friends and family, then I forced myself to live on this schedule for a month and finally I got the hang of it.” Sometimes it's literally changing everything, “Yeah I lost the pounds because I went to live in the Netherlands and school was a 50 minute bike ride from my apartment either way and then I didn't have any friends so I joined the university's competitive ultimate frisbee team, so like my dinner most days was bought that day after practice in a 5 minute trip through the grocery—a raw bell pepper, a ball of mozzarella, maybe some bread in olive oil—I didn't have time to cook anything big.” Or sometimes it was imposed top-down but with good motivation, “yeah, I really wanted to get a role as an orphan in this musical, so I dieted and dieted with the idea of ‘I can binge once I get the part, but I have to sell scrawny orphan when auditions come round soon’ and like it sucked for two weeks but then I got used to the lifestyle and I no longer wanted to binge, funny how that worked out.”
There are so many different stories, and yes they never look like we would imagine success to look like, but being pessimistic about the existence of the solution in general because there's nothing in common about the success stories, I don't know, seems to throw the baby out with the bathwater. There is hope, it's just that when you are looking at the systems map, people get in this rut where they're looking for one thing to change, but really everything needs to change on that map, you've created a big networked dependency graph of the spaces you need to interrogate to figure out whether they are able to cope with the new way of doing things and, if not, are they going to grind their heels in and try to block the change. There's still use in it, you just need to view the whole graph holistically.