I'm guessing Purism is trying to make it as easy as possible for non-technical people to make the leap into decentralised services.
If you promote separate apps and separate services under separate brands, it can (rightly or wrongly) seem confusing and overwhelming, especially on decentralised networks where there's no central site.
A lot of people aren't that interested in computing, and don't want to have to think too hard about who to sign up with.