When you have contractor status, are brought into a meeting where they say you are underperforming, not committed, and turn deaf ears on however you try to justify yourself... and you end up leaving the company... you may have been fired.
The biggest mistakes you made was a) still being a contractor b) not asking for severance if you would opt of of claiming unemployment on them.
I don't think you can fairly say a person was fired simply because s/he quit following a dispute with the boss. Maybe the person would have eventually been fired, had s/he not quit. But that's pure speculation.
There's the cliched "you can't quit, you're fired"/"you can't fire me, I quit" scenario. I think the question of who terminated the relationship is less clear there. But that doesn't seem to apply to the story the author tells.
Why quibble over this? Because the distinction between being fired and quitting matters for the employee's future prospects.
> The biggest mistakes you made was a) still being a contractor
How do you know the author was in fact a contractor? The author didn't post his offer letter, tax forms, or other similar documents. So we can't know for sure. But he says he understood himself to be a full-time employee. Some of what he describes, e.g. the boss's comments about hours, seem to support this view.
The distinction only matters as to whether the OP has leverage over severance or goes after unemployment.
OP's future prospects are hurt either way if the next job calls that PM as a reference -- and slightly by this blog post.
These are the scenarios I was thinking of. They're the reason the distinction matters.