"That's like... your opinion man."I appreciate a good Lebowski quote, so props on that one. :)
Is my use of "never" a bit much? Ok, fine. Let's dial that back to "rarely." It's rarely a good idea to quit a job without another one lined up. That is true for precisely the reasons you articulate here:
"a narrative pushed by our keepers that doesn't bear out."
So you admit the presence of "keepers," i.e., HR folks and their processes. These keepers exercise a lot of power in the job market, and they stand guard over many (most?) jobs out there. Bad ones and good ones. Most job-seekers will have to deal with their processes when looking for jobs.
"Typically the best places to work have a respect for sabbaticals, leaving toxic work environments, focusing on personal growth etc and that certainly has been the case in my experience, and I'm nobody special."
Sure, but getting into those companies in the first place often involves a resume screen by an HR type. Companies can be amazing, progressive, intellectually stimulating places to work, and still be guarded by a gatekeeper who either isn't equipped for, doesn't care to, or doesn't have the time to mentally process any abnormalities on a resume.
My point isn't so much that gaps on a resume are absolutely and necessarily career-killing. Far from it. Rather, my point is that it's generally a good idea to minimize them. Such as lining up something else before leaving one's current job. Again, this is because the world works a certain way. It's not a "narrative" being "pushed" by anyone. It's the unfortunate reality of the job market. (The effect is magnified at least tenfold for non-developers, too. But that's a different story.)
I realize there are exceptions here. Developers are in incredible demand right now, and can thus afford to do things (such as quitting without a gig lined up) that non-developers usually can't. And then there are the folks who are connected enough to land a job whenever, wherever. I would advise anyone at a job he hates, thinking about quitting, to consider where he falls on these dimensions. Are you the kind of job-seeker who draws a lot of water in this town? If so, great. If not, stay sharp. Look before you leap; that's all I'm saying.