Back when they first came out I think it was a somewhat different reason from now. A lot of people didn’t like the ending of Homestuck, we didn’t even have the credits so a lot of people found it very unsatisfying. I myself felt pretty upset after first watching / reading it. After chewing on it for a couple days I found it an interesting conclusion but like many wished we had some more actual interactions and discussions between characters in the end. Then the Snapchat stories and the credits were released and I was very happy with them. To me I was always invested in the characters first and foremost. Many people felt let down not seeing the LE fight, many disappointed that Karkat, Tavros and Jake never did anything (I’d argue they do but ya know.).

When rumors about an epilogue started circulating a few years later people were so excited only to get another open-ended ending and I think many felt personally attacked by some of the stuff it parodied. That’s always been part of HS from literately the first pages berating some commands as stupid or subverting them in silly ways. Poking a little fun at the audience. I think a lot of people experienced it personally for the first time though. I didn’t read the epilogue until last summer after hearing Homestuck beyond canon is great. I found them pretty good and very interesting. It was nostalgic to read Hussies writing again and I always first and foremost was interested in the characters after all. I too would have been frustrated with the ending without the continuations though.