I think you will find that most of the devices that end up going to people like the LR Group and others are in fact either items that are only just outside the warranty period or still in the warranty but have deemed by the local Apple Store / genius bar to have suffered "liquid damage" and therefore are not covered by warranty as a result. When some of these machines find their way to LR for instance, and opened up, show zero signs of liquid damage other than one of the detection spots have changed colour and the fault has been discovered to be something as trivial as a ribbon cable not fully seated properly etc.
Others that have been liquid damaged, have been totally recovered and restored back to health again be the replacement of the chip which was subjected to the liquid damage resultant corrosion of the connections and or pads / traces and the repair carried out without any difficulties by the assistance of a donor board surrendering its chip or the pad / trace being rebuilt and all of this without the device being "bricked" or compromised in any way whatsoever.
As to the Secure Enclave, how does this prevent the items from repaired using genuine parts supplied by Apple I fail to see this argument being valid. As we know Linus had an accident with his new iMac Pro and admitted that he broke it and was willing to pay Apple to repair it for him, and their response was no, he would need to buy a complete new system costing thousands of $, they were not able to get the few parts required to fix it for him.
He was not looking to do it himself, or go to a unauthorized agent, he went direct to Apple themselves who declined to help.
Apple still continue to sell items that they know to have bad design flaws in them and often fail within the period of warranty and this has been the case for a number of years now, keyboards being one of these items affected.
This is NOT me just bashing Apple for the sheer hell of it, I have an iPad Air, use it daily and I love it, I also have a Samsung SM-T520 which is the same age, has a larger and better screen, can be user extended memory wise via microSD and can be connected to external devices like hard drives, USB drives etc. The iPad runs rings round the Samsung when it comes to things like speed of games and screen updating etc, so I'm not anti Apple, just anti their attitude towards getting items repaired once out of warranty and their whole outlook on customers in general is one of where they see the customer as a walking cash machine for them.