For a lot of fandoms, the top kudos'd fics represent what was being written at a time when the fandom was big, experiencing a surge of popularity, and sometimes when not much fic was around yet full stop so everyone read everything. The couple times I've wound up with fics that show up to people taking this approach in a fandom, that has been how it happened. They're nowhere near my best work- they were all written over a decade ago, for a start, lmao- but they got posted at a point where they were just being read by lots of people desperate to read fic for a new, popular thing!
It's made me super aware that this means this method just isn't how you find the stuff you will like most. It's how you will find stuff that appeals to the widest audience, which is completely different. Lots of people finding a popular ship's fic Pretty Good is not always the same as something that is super amazing and creative but, because it drills down into doing something really specific or niche, just catches less people's eye!
This is why I think getting ourselves into the habit of reccing stuff and asking for recs more is needed, tbh. Curation is always better than number crunching. The NYT bestseller list isn't a record of the Best Books TM, so why would fic be any different, yknow? You can totally check the bestseller list for ideas on what to read. Sometimes a book is selling because it's amazing, after all. But it's probably best not to assume it's all you'll ever need.