Let me know if my math is wrong: it means that 5 people are on the moderation team of 18.4 subs. The 500 top subs often have mod teams from 20 to 50 people.
Bringing up that stat doesn't seem really relevant.
I'm saying it probably doesn't take much man power to moderate these subreddits as you might think. Bring in a team of 5-10 full time workers would probably be enough, tbh.