To be honest, it makes perfect sense.
Imagine if the battery in every smartphone was standardized, so instead of every single phone having a different size/shape/connector/rating of battery, there was one design, so you buy your cheap phone, then decide you need more juice, just go to the shop, buy a different battery, no worrying about compatibility, or buying the wrong one, etc.
Make the ram/storage chip common in all phones, so people who are ok with 1GB Ram & 8GB storage are ok, if someone needs 8GB Ram & 256GB Storage can just buy a different chip and swap it.
That to me is the key. Don't go for the whole phone like this/phonebloks, but start with the bits that can be easily standardized, and need the most variation.