[throwawaybutwhy]

Google Search is not to blame for SO's decline.

Toxic deletionists are part of the problem, yes. But they are the literal dregs at the bottom of the bottle when all the good experts have left or burnt out or converted to deletionists. There's no way to find great questions that would make their talents shine.

And here we come to the next point - the company behind SO stopped investing dev time in improving the core experience. Yeah, they were also overrun by vitriolic politically motivated folks, but this is only a lateral plot line. Rearranging CSS, coming up with brand-new bug-ridden editors, concocting impossible get-rich-quick subsites parasitizing on the main site's popularity against the opinions of old-timers - here are just a few examples of brainless PM activities over the years.

As a consequence, Stack Overflow is dead. As in, still twitching from a combination of ideological / greed-fueled Cordyceps firing up random neurons. But yes, mostly dead.