Just an anecdote from an Apple user - my Mobo and GPU fried in my 21.5" iMac (I'm sure the poorly ventilated aluminum casing didn't help). While it was possible to repair it, my options were restricted to replacing the failing hardware with hardware of the exact same specifications as the original pieces (which were, at that point 4-5 years old) - and paying the same price for them as when they were new/current. Meaning, no possibility of upgrading a 5 year old iMac. Further, the cost of repair - with outdated hardware - would have been more than the cost of just buying a new iMac, not including labor (as per an Apple authorized repair shop, as well as the Apple Store). I wasn't keen on doing it myself (which I did suss out on iFixit) just due to needing to remove the screen to gain access to the interior, risk of damaging the port/cables to the screen, and issues with fan management triggered by replacing core components. The limited space also meant that I could perform only minor upgrades - no upgrading to a current GPU or a better motherboard.

So while it is possible to repair them, and even doing so on your own, they make it very prohibitive to do so.

I enjoyed my iMac (and still have my MacBook Pro, iPad, and iPhone - could definitely have been considered a fan of the products), but have since gone back to PC just for the sake of being able to keep it updated, and the ease and cost efficiency of upgrading (plus, getting a decent base gaming rig was still less than the cost of replacing the iMac). Further, reducing waste - I'd rather invest into a well-built PC (to my specifications) and make periodic upgrades, as opposed to trashing an iMac every 5-7 years for a new one.