Activity levels vary in both places... there was a time when people were posting here every day, and the reddit was very quiet. Nowadays the reddit has a little bit of activity now and then, but nobody posts much here. Seems a little random, but hey.
To me it seems pretty clear - Otho's ability is that when you say "I will spend favor", he says "No, you cannot". He prevents you from making that choice. With the auto-favor abilities, there is no choice involved, it just happens automatically. That seems to me to be why Otho says you cannot earn and spend (voluntary actions), and the auto-favor abilities say they generate and add (automatic effects). Meaning Otho doesn't prevent them.
But that's just an interpretation - it is possible the intent was otherwise. It's always possible that the intention was different with any interpretation of any rule.