Sounds like we have two different discussions here.
ESD is unprovable as failure cause without access to the kind of electron microscope wiretap has access to, but I've seen the pictures of ESD at that level and they are clear enough. I've also seen concrete examples of differences in return rates between PC shops that did an ones that did not implement good ESD practices. ESD is real and causes failures, lots of them - it just takes a long time for the failures to manifest themselves. Given we're talking about old crap and keeping it running over long periods, we should all care about ESD, even if we don't see stuff going up in smoke in front of our eyes.
But the original question was about precisely that: spectacular failure of PSUs causing things to die instantly.
I've seen a lot of hardware and seen a lot of it fail, but never actually had a clear-cut case of something dying due to bad PSU. The closest I came was a system I picked up off the street, with a motherboard with completely toasted ISA bus. Any card in any slot would short the system out - although it would actually start POSTing without ISA cards (and yes, I used my ATX2AT smart converter here, otherwise I would have blown the next PSU trying to discover this). The PSU was also blown - bad caps and a melted MOSFET. Either a short in the ISA bus killed the PSU, or the dying PSU caused the damage to the motherboard. Can't say. Both were bottom-scraping low-end (PC Chips M537DMA board and Q-Tec "300W" PSU), although I'm inclined to blame the PSU sooner than the board.
Apart from that what I have seen is that badly regulated power exacerbated other issues. During the capacitor plague, boards with dodgy caps connected to crap PSUs seemed to die a lot sooner than identical boards behind good ones. That said, the all die eventually. It's also interesting to note a lot of the experiences mentioned in earlier posts date to exactly the same plague era (1999-~2004), and that PSUs also contained bad ones.
I have however had several instances of PSU's exploding and/or literally going up in acrid smoke with no short or medium term damage to connected components. YMMV and usually you get lucky. However that also applies to playing Russian Roulette, so saying you do is NOT a recommendation to use subpar PSUs. I am however in the camp of using good quality period PSUs rather than exclusively using new ones, and I'd rather have a 20-year old known-good PSU than a new one of dubious provenance.