What are the benefits of an expertly curated learning pathway?

Like that provided by a major publisher's textbook - CPM, a school district's mandated curriculum - IM's Open Up Resources or a learning game - ST Math, Dragonbox, or Amplify Fractions.

I ask this question with no particular age-level in mind, but I could see how the younger a learner is, the more useful a defined learning pathway would be - partly due to the inexperience of the learner

Research has been done on the idea of learning maps as a way of assisting learners along a learning pathway. See Gates Learning Maps projects.

One led by Jere Confrey's team has had some interesting research results and a design concept.

However, I still find it difficult to believe that the future of learning will involve standardized linear learning pathways... true personalization will bend and weave the trajectory of each learner, right? As Knewton described or InBloom once visaged... Or as a math prof recently argued to me, "Whose canon?" when discussing canonical examples to teach undergraduate intro stats.

In an age of brokering experiences, I offer my non-expert postgraduate data science pathway and ask the question another way,

Why pay for an expert's subjective structuring of content when you can structure your own learning based on your own personal interest and passion projects for free?