After successfully upgrading this laptop, I will add more details on why this is such a pain to work on:
(1) Motherboard is relatively easy to service by itself given that it has to be removed to service anything else, but all the user-upgradeable parts are facing the keyboard (as noted in the article), which makes it a chore to do any kind of maintenance or service on anything other than the motherboard itself. Memory, SSDs and battery all require that the motherboard be removed first to access. Likewise for the thermal modules.
(2) Battery has no internal bracing so needs to be handled very carefully, as it is long and can flex easily. May even be a fire hazard if you're not careful.
(3) Many cables on motherboard that need to be disconnected before you remove it. Small zif connectors. Not impossible if you're used to SERVICING laptops or working on custom electronics. Servicing means replacing motherboards, disassembling screens, and similar things that require COMPLETE disassembly of the laptop. For average users used to just popping off the back cover and changing ram or HDD/SSD, you can't do that here. There's a high likelihood of accidentally tearing ribbon cables if you're not familiar and comfortable working on laptop innards.
(4) The motherboard itself has a fair amount of flex, like the battery, so must be handled very carefully to avoid damage. It's also not easy to remove, even after everything is disconnected. It took me ~1.5 hours to figure out how to disassemble this without damaging anything as there's no publicly available service manual, and the battery, motherboard, and ports all require delicate care, the kind you won't get from your average on-site or in-store repair tech, who tend to be more focused on speed. [Side note: The wireless card needs to be disconnected and pushed through when removing the motherboard since the antennas are attached underneath.]
If you're comfortable spending 2+ hours figuring out how to carefully disassemble and reassemble the laptop to avoid breaking anything (faster after the first time, but if you get too comfortable, you will likely break something), it's possible to upgrade the parts, but most end-users or repair techs will not have this kind of time, experience, or patience. Maintenance on this notebook is not for the faint of heart.
It's a solid laptop, but they engineered it in such a way that the internal parts are not meant to be serviceable by end-users. For your average user who never worked laptop repair, or who does not have extensive experience disassembling small electronics, the parts may as well be considered soldered in place.