You've just proven what I've said previously: Misery loves and even demands company. If the evidence doesn't fit the hypothesis, then the "losers" (your term, not mine) don't want to hear it.
Fact is, the "October surprise" or "October glitch," if there was one, didn't affect everyone. So the usual unsupported claims that Google has "cut the payout" or made other across-the-board changes that have hurt all publishers are demonstrably false.
As for the idea that a "perfect storm" or a "trifecta" would be limited to a specific niche, no one has suggested that, and the notion doesn't make a lot of sense. It's far more likely that a combination of circumstances would affect publishers who fit certain profiles in terms of traffic, clickthrough rates, the number of ad units per page, various Google Search scoring factors, or...? We just don't know. What we do know (as always) is that the experiences of neither the losers, the winners, nor the in-betweens are universal.
Getting back to the nominal topic of this thread ("Time to leave AdSense may be approaching"), I'll simply add that it is reasonable to ditch any revenue source that isn't working for you--whether it's AdSense, a display-ad network, paid subscriptions, or the WidgetSales.com affiliate program. Still, it might not hurt to keep a limited number of AdSense ads on your site for monitoring purposes, since what's down today might go back up next week, next month, or next year.