Thanks @traveller7761 - appreciate you taking the time to read and you've come up with an idea there. Sounds quite technical. I don't know the answer as to why the Conversion mechanism exists.There is an area of the white paper which is interesting reading: see page 10: Minimising Abuse of Conversions: https://steem.com/SteemWhitePaper.pdf - it explains why a two way mechanism isn't in situ.