I find it strange that searching in the text of the paper and the commentary on it for "documentation", "tutorial", "errors", "help", "faq", and "doc" turns up nothing. Anecdotally, salespeople who try to persuade companies to adopt a payments API have found that it is very useful to have both tutorial and reference documentation. I think if you're asking questions about software adoption, you'd want to study the impact of documentation availability and clarity.