Medical doctors have a fairly well understood job, at least on the surface.. I think. People arrive in front of them, and describe their problems with a specific mind to get those problems solved. A medical doctor observes, listens and examines, and then takes action based on incomplete information. They may decide to run tests, or take a best-effort guess at a treatment plan. At this point, they are prescribing to solve problems which the owner of the problem cannot solve themselves.
Engineers sometimes act like doctors. Specifically, I have often acted in this way in the past. At times, this works out well. A confused set of engineers describes their issues, and I can respond with strategies to fix them.
However, when an engineering effort reaches a certain size, this simply does not scale. As the doctor, you will either be crushed under the weight of so many requests, or you will be operating under such stress that your information will be wildly inaccurate and your understanding of each team's problems will be skewed.
I've been in this situation, and often start to draw tribal lines subconsciously. The use of the word "they" instead of "we" is a good indicator of when you've decided people are not part of your tribe. And by drawing these lines, you shrink your sphere of concern to a level that allows you to continue prescribing solutions. If the other tribe enters, they are not looked as a whole group with real issues. They are part of "they", and thus get the same answer: "Do it my way or be gone."
I've often felt that this was justified. I've said things to myself or others in my tribe like "We are doing something a bit radical, so it's natural for them to fight it." or "They're just frustrated because this is so different from the way they do things."
This is all garbage. This is caused by trying to prescribe and act like the doctor, rather than being a collaborative and helpful engineer. Collaboration means listening, and applying a reasonable amount of both scepticism and trust with your peers. It means forming working groups and being "we" and "us", and making sure that the members of that group that aren't part of your usual tribe are aware they are peers in the effort.
The main reason to do this is trust. Without trust, you start to make decisions, conscious or unconscious, that exclude the untrusted parties. Pretty soon it gets even less comfortable because now you have secrets, and likely they do too.
After this, whoever is doing the prescribing (such as me in some recent dealings) finds themselves prescribing solutions to the wind, because those who were untrusted and treated as inferior will find a way to go forward without you.
So, I hope that somebody finds the advice I have recently given myself useful: collaborate, avoid prescribing, and always be aware of the impact your actions may have on trust.