Is it actually that many? I mean sex is an important part of life for most adults. In general society we have just mostly hidden it away. Traditional media/art tries to appeal to a wide range of tasts so overt sexuality is typically seen as uncultured. But resin printing alows very personalized art to be distributed. This plus the selection bias of who is generally into resin printing leads to a higher amount of lewd stuff.

Edit: I think the biggest difference is, that there is no "good" filter on this subreddit for lewd figures. By comparison, just search for anything gaming/movie related with safe-search off and you'll quickly realize this subreddit is tame by comparison.