It seems much more likely to me that life started as an 'autocatalytic set' of molescules, each of which contribute to catalysing reproduction of the whole set,

It seems much more likely to me that life started as an 'autocatalytic set' of molescules, each of which contribute to catalysing reproduction of the whole set, rather than a single strand of active RNA that can reproduce itself. If we look at life now, DNA does not reproduce itself directly, there is an entire ecosystem of chemicals that reproduces itself collectively, using RNA/DNA as a blueprint. The question then is how a set of molecules encoded itself in RNA, but I see that as much more envisionable (eg some RNA, and a host set of catalysts) than a self-reproducing strand of RNA appearing all at once.