We used to have this right, but it feels like somewhere between 2010-2015, companies realized they could make more money by disallowing simple replacements.
I used to make some money as a kid by buying batches of broken Iphone 3G/3GS's on ebay, replacing parts on them, and then re-selling them myself. Practically any part of that device could be replaced in less than 30 minutes with $15 worth of tools.
I have a 2012MBP and a 2014MBP that I gave to my family that are still serving their purposes after a few quick(and cheap) battery, RAM and HDD replacements over the years.
I don't expect my 2019 MBP to last more than 5 years without costing me at least several hundred dollars more when I inevitably have to bring it to the Apple store for them to fix something that very much used to be user-fixable in a matter of minutes.