> This would be less a problem if brands followed some kind of trend in overall reliability, but it seems like individual models vary widely in quality even within a specific brand.
This is, frustratingly, incredibly true. Even otherwise good products will tend to have some single component with a significantly lower lifespan than the rest of the device. This is compounded by the fact that everything is now manufactured to such exact specifications that it becomes effectively impossible to replace that piece with a higher quality one they should have used in the first place.
Then you have the insane number of SKUs a single base device can generate, and it becomes difficult to tell whether the thing you're holding in your hand has the shitty version of that component, or the better one. Sometimes it's even the same SKU and there's a range of bad serial numbers (typically because the manufacturer got a bad batch of something from one of their suppliers).
My guess is that the sheer number of parts in many modern products has drastically increased the chance that a device fails. My office has a water cooler with a purifier, and a spout for hot water. It broke and a guy came in to fix it. There are 2, 2 circuit boards in that thing! For a water cooler. How many parts are there that could fail and brick it? How many would a more primitive water cooler have? I just can't believe the simplest water cooler we could invent has 2 separate circuit boards in it