I am not meaning to paint those who work on AOSP or third-party ROMs in a bad light. The work they do is terrific and great for the community. I also do not mean to dismiss any of the fantastic work that Graphene brings to the Android community.
I am simply stating that the biggest difference between Librem and Android is that there are more hurdles to jump through to provide a completely usable and free AOSP phone to an end-user in 2019. Android has been made to host a Google ecosystem, where the Librem 5 is being created to host an open ecosystem.
It sounds like the Purism team identified this issue ahead of time and decided to provide that open hardeware platform for us.