TPMs don't impede your ability to repair anything. Soldered ram is a hassle, but it's not any more malicious than soldered CPUs. It's a design choice, and tradeoffs had to be made.
It's suggested that many such devices might be stolen. But there will also be devices where the user forgot to wipe their data (or didn't know how); or devices that are only just damaged enough that you can't wipe the user data.
Probably an official Apple store can refurbish them somehow, but that is the NOBUS / EARN IT argument.
There are some stories like this: https://www.vice.com/en_us/article/akw558/apples-t2-security...
It's suggested that many such devices might be stolen. But there will also be devices where the user forgot to wipe their data (or didn't know how); or devices that are only just damaged enough that you can't wipe the user data.
Probably an official Apple store can refurbish them somehow, but that is the NOBUS / EARN IT argument.