I am now playing as Emperor Napoleon, and indeed, each sanction counts as one point towards the combat strength of land units. In the exploration era it's very easy to maintain 6+ continuously, investing influence in only three enemies (my current situation, where they're already sanctioning me all the time anyway). It's a small amount of influence to spend, and you can have suzerain city-states and even research or cultural agreements with other civilizations. In Antiquity, especially in the first half, it's more problematic because your enemies aren't fully defined, and influence is scarcer.
In short, I see him as an entertaining military leader because he's somewhat different, but not one of the best. Gold and culture are welcome, but I don't see his strength there.
