I think a guest account should be able to be a BENEFICIARY of a comment/post... but not sure about their ability to make comments and posts... that gets into the whole RC system thing. That means they have a impact on APIs, they have probably impact on spam, on votes and all sorts of systems, like account metadata any everything because then you need pictures etc... that doesn't make them very light. It seems like 3steem above free. haha ... aka normal account.

And every interface could easily solve guest commenting without the need for it to be directly in the blockchain. We're gonna do it pretty soon without light accounts... but it would be so much better if there was a place to send the beneficiary rewards of those posts and would be nice to turn them into normal accounts quickly.