NOT volunteering to become an author of the plist SRFI, but I came up with some text that might be useful for the Abstract and/or Rationale:

Property lists (plists) are a venerable LISP collection type, simple lists with alternating keys and values [could include something like "'(k1 v1 k2 v2)" here], and have some advantages over the Scheme standard of association lists (alists).  This SRFI provides tooling to make them first class citizens in the Scheme ecosystem.