FWIW, I'm in the UK, in an area where the power supply is less than brilliant. We don't get many complete outages, but moderate surges and brown-outs seem to be happening all the time if the behaviour of a UPS is to be believed.
The working life of our electronic devices was surprisingly short across the board for the first few years after we moved here, with many formerly reliable devices all failing within a couple of years of the move, including (coincidentally or otherwise) multiple consumer-grade broadband routers. In contrast, in the years since installing a UPS for all the serious gear and at least basic surge protectors for everything else that plugs into a wall socket, we've seen almost no surprising failures of that kind.
Of course we don't know for sure whether it was really the dubious power supply that was responsible, and as other posters have mentioned there are several alternative explanations that would also make sense. But given how many things we saw fail within the window where the power supply was bad, and how few failed before and afterwards, the odds of the power supply being a factor seem quite high in our case.