The SOM connects to the mainboard with 4x 80-pin tiny connectors. If you miss the little warning on the silkscreen and lift from the wrong side, BAM, two broken connectors.
Purism said they would sell me a replacement SOM, but they're not really communicating now.
For one, I may find that something isn't working and the chips may be relevant to that. For two, if I want to re-purpose the kit for something in the future, that list of chips will let me know if I'm going to need to write a driver for my target OS.
You can gather a lot of this info from a running OS, but it's much quicker and more accurate to just look at the chips in my experience.
(Purism did finally send me a return shipping label for the SOM today)