Where I work we had an old Performa 250, and that thing ran like a horse. It was very basic, but ran faithfully day in and day out until they finally upgraded to new machines (Windows) that we've had trouble with. I take good care of my computers, so I can't say from experience that Windows stuff fall apart faster, but I find the Windows OS does 'fall apart' (or at least begin degenerating) within the first year or so.
I think here that both sides there are well built and poorly build computers though due to the abundance of PC manufacturers all aiming to tick every box at a set price point does let down the industry as a hole.
But this is what we demand, we demand every feature possible and it to run everything fast wile being able to make our own upgrades and for it to cost as close to nothing as possible. What you get is a compromise, and this comes in many shapes and forms including: poor design or lack of any design at all, ineffective cooling, bundled software and stickers to subsidise the cost, cheep error prone memory, and often poor battery performance.
What consumers should demand is that we'll pay a little extra to get that bit extra quality, but then you get to the arguments about Mac's being expensive because people want all the boxes ticked and can't understand that costs more money.