You hit the nail on the head when it comes to page builders. As far as I can tell, most of then try tackling the problem of expensive development by enabling nontechnical users to build sites in one of two ways: customize with a GUI (which is either comically limited or harder-than-code complex) or choose from an endless list of pre-built components/templates (which just turns one development hour into three research hours).

primo enables end users by enabling developers by offering immediate access to those same productive tools and making the code as accessible as possible.

As to your comment on single-source-multi-output, primo will be able to expose all the content on your site at an endpoint soon, stay tuned.