And managers are technically workers too. There's no reason to put them in an ivory tower and assume they can't hate their job, hate people they work with or want to exact revenge for some wrong done against them.
Check out the difference a little wordsmithing makes:
* 'this deadline is unrealistic' — “id love to be able to get all this done for you, and with 8 weeks left, I’m only going to be able to get through half of this; let’s sit down and figure out what we can deprioritize without compromising the core of our next release”
* 'we can't continue at this pace, we have to have time to address some serious technical debt' — “I’ve noticed im having trouble moving quickly in the codebase with the level of testing we have right now, I’d love to lead an effort to improve testing and testability. Let’s resdefine ‘performance’ to include velocity, and with this new metric I’m sure we can find some time! Happy to do the leg work here.”
* 'I heard marketing saying that we can do X, but it isn't true and to add feature X would destroy our timeline' - same as 1: “I’d love to be able to get X out for you in the next release, and to do so requires we cut a few weeks scope elsewhere in the product — let’s sit down and see what we can deprioritize without compromising quality!”
* 'Adding more contractors isn't going to speed this up or improve the quality, we need time not warm bodies' — what will? “Let’s see if we can save the company some money by finding a way to work more efficiently! I’ve noticed x and y, and I’d love to take the lead on it. Let’s define some metrics to show this is as good as or better than bringing in some more contractors! The finance team is going to love our proposal.”
But then, maybe it's just that I'm prototypically toxic. And why I've always been happier as an independent consultant. Because I've tended to have slack to declare bullshit.
If someone was using the term "toxic" simply because of those behaviors, I'd say they were just using the wrong word.
Based only on what you wrote, another possibility seems to be that some aspect of how you communicated those concerns, or some other aspect of your behavior entirely, is what caused people to consider you "toxic". It would be interesting to hear your former manager's view of things.
In my own experience, I've had plenty of cases where my own view of my conduct was very different from how my coworkers viewed me. The cumulative impact of miscommunication and my occasional lack of self-awareness has caused me some serious grief.
If they're all doofuses, it's time to leave!
But, if they're reasonable people, things will change for the better.
* 'this deadline is unrealistic'
* 'we can't continue at this pace, we have to have time to address some serious technical debt'
* 'I heard marketing saying that we can do X, but it isn't true and to add feature X would destroy our timeline'
* 'Adding more contractors isn't going to speed this up or improve the quality, we need time not warm bodies'
Of course none of those things were what my manger wanted to hear. When things inevitably went south it all came down on me and I was managed out of the company. I'm much happier now, as I see that the job was what was toxic. My manager wouldn't listen to me and I wouldn't drink the kool-aid that all was well. In fact, I saw it as my responsibility to share these concerns and to not just go with the flow. Now that I've had time to look back on it, I just think that is his management style: grind people to the bone for all that they are worth, then throw them out and repeat to the next poor sap.
Anyways, the article is about toxic workers - but if the managers are the ones deciding what is considered 'productive' and who is 'toxic' then that isn't a very complete view of the actual environment.