realistically I think the main reason for this is that homestuck comics are primarily a visual medium. while having good writing is def important for a good mspfa or whatever, a lot of the appeal of homestuck/mspfa comes FROM said pretty pictures. i'd consider one of the standout parts of homestuck to be it's formatting: the singular panels combined with the individual commands make it flow super well for readers while also giving a steady flow of visuals and writing to take in (versus, say, a regular comic where you have to fit all the dialogue into said panels along with the art).

good visuals also usually get the most attention because
1. it's the easiest thing to latch onto if you're just an average person consuming stuff casually
2. good visuals can help strengthen existing ideas, concepts, and even just dialogue a LOT more than you'd think

i think the example i'd use for this is s33k the highb100d (https://mspfa.com/?s=60015) because it kind of covers both of these aspects. the art in this comic is pretty damn nice (as well as having some super nice choreography in it's panels when they box) but it ALSO tells a well-written and engaging story that covers what i'd think is a decently common concept in the fandom (what if nepeta showed up a lil earlier) while also covering equius's character and beliefs relating to the hemospectrum.

a lot of the coolest parts in this comic are heavily supported by the artwork in said panels. for example, panels 55-59 hit SO much crazier when you are actually SEEING equius get up, wounded as hell and limping all the way over, just to try and plead with gamzee to leave nepeta alone. this part was fucking SIIIICK and it really sets the tone for how desperate equius is acting right now. another part is just like, the entire part where nepeta and gamzee fight like that shit is so cool and it choreographs well.

you could 100% create s33k the highb100d as JUST a written work (and i think it actually started that way on the creator's tumblr? but im not sure) but it would be so much harder to make these moments have the same impact with just words alone. you can use all the metaphors and similies and weird formatting in the world to write about equius's inner turmoil and conflicting feelings and beliefs watching nepeta get her shit kicked in as he fights to stagger over to gamzee, but like that one saying goes, a picture is worth a thousand words. you can describe a fight scene all you want, but nothing will actually beat seeing it for real

i'm not too versed in homestuck fanfiction/that entire scene (i did do a bit of fanfic stuff in the past, but not for homestuck) but i'd imagine it's super hard to convince people to read a cool homestuck fanfiction solely because they are, at their core, gonna be lacking what i'd assume to be one of the main reasons people read homestuck and homestuck-related stuff: the visual aspect of it.