That’s probably why people like reddie/stenbrough so nuch, because they achieve that Balance. That yin and yang.
Stan is melancholic, Bill is choleric, Eddie is phlegmatic, Richie is sanguine.
Of course you could easily flip Eddie and Bill around and in which case we’d still achieve balance and harmony.
Stan is introspective, quiet, sad. Whether Bill is passionate and fiery or Bill is analytical and logical, both cases contrast to Stan and fill in the gaps he has, cover his weak spots.
And Richie is free spirited and energetic and at least pretends to be happy. Whether Eddie is brash and bold and angry, or serious and grounded and thorough, he complements Richie.
Both duos complete each other in both cases. But it’s not like it’s mandatory. All the ships bring something to the table. And none of the Losers perfectly fit into a Four Humors analysis just like none of them perfectly fit into a Harry Potter Sorting Hat analysis. Richie gets very angry at Bill. Eddie can be very goofy and mischievous, etc.
Also yes they’re all skinny white boys. So take that into account lmao! People are going to gravitate toward them anyway. But I think it does explain a little why steddie and bichie (or stozier and kaspbrough for that matter) aren’t as popular.
Bitches love classic literary character tropes and the opposites attract mentality!