Loli isn't related in the way those are and it's not just tangential. Trap shota isn't "femininity+dicks", it's cute
, feminine little kids
with dicks. Common character types in doujins are little brothers/cousins, crossdressing schoolboys and so on. Moe is emphasized and so is submissiveness sometimes. Lolis are cute, feminine little kids, share doujin themes and are even often made by the same artists. Obviously they're miles closer ara and bara. People who like trap shota also like loli but hardly ever the other things you mentioned, precisely because they're so similar.
The board hasn't lost its focus, all loli discussion goes to /delicious/ by default. Besides the doujin dump which is dead storage my intention is to let loli be posted if it's relevant in trap shota threads (such as comparing stories, characters and artists) because nobody will find it disgusting.