I have had a hard experience with that (as an IC) as well, finding myself isolated at my current job and unable to exert any influence. All the developers I work with have been at the same job for 5+ years and don't have a clue that the team is massively underperforming, their release and operational support processes take much more work and are less reliable than the same processes at other companies, the codebase seems almost intentionally hostile to new contributors (to the point of caricature; any description would come off as comic exaggeration,) but they think they're doing great and have all the answers, and every time I suggest improvements they respond like, "Well, actually, the reason it's better to do it our way is because..." and from that point on they are talking and not listening. All the other developers they hired in the last five years are gone, probably because they weren't listened to.

I don't know if the isolation happened suddenly or gradually. I realized it all at once, but by the time I did, it had been happening for so long I don't know how it started. Somehow people stopped telling me what was going on and stopped consulting me on new decisions. I am the last person to find out about anything. One part of their existing pathology is a background churn of unilateral, unannounced, shuffling-the-deck-chairs "improvements" that cause a lot of errors and interruptions without making a worthwhile difference, but this is different. Even the changes that are formally talked about are talked about without me.

I know that leadership has my back (they came into the picture more recently and can see that the team is underperforming) and they are planning changes that include me, but other than management, which is detached from day-to-day work, I'm on an island. Reading between the lines, I think I was brought in to try to fix the team, but without any management authority (and management not involved day-to-day) and with the team just ignoring my ideas and trying to assimilate me into their way of doing things, I have accomplished almost nothing on that score. Meanwhile, my social isolation is such that I can't stand to stick around much longer. I am going to go somewhere where I can be part of a team again.

EDIT: Reading the article through fully, I think I should learn from his characterization of "swagger" (though I don't think the word is quite right.) When I wasn't listened to after repeated attempts to make the same point with the people who needed to hear it, I shouldn't have stopped talking. I should have kept saying the same thing whenever it was warranted. I should have talked louder. I should have taken my points to venues that included a larger audience than just the people who needed to act on them. I should have pressured management to put their weight behind me. I didn't do these things because I didn't want to be an asshole, and I didn't want to alienate people, and maybe because I was afraid of inviting open aggression against myself, but I should have been prepared to stand up to that. Why was I avoiding confrontation instead of inviting it? Maybe because I wasn't confident in my ability to argue my points in the face of hostility, but if that's the case, I should be practicing it more, not avoiding it.