Requests for filtering options are certainly valid, but I would not want to see a specific genre targeted without very good reason (and there are regulations here, such as "live action" graphic images are not allowed).
As far as I know this is a developer site first, and a storefront second. There is a strong emphasis on artistic freedom here, which I personally value even though I don't play horror games. As a player coming to the site, it should be understood that creators here have a lot of independence and that you have to exercise your own judgement when browsing. And I think the importance of being able to just click on "browse" and have your preferences catered to is overblown. It isn't that hard to click on "Top Rated" and suddenly not see many horror games...
The reason "horror" is "targeted" by so many threads is this: the first page in browse will show 36 items on load. There are days when over 30 of those items have the tag horror. And those days are many. As of this writing it is 32.
Now is the horror well liked? If you go to the top rated section in browse, only 10 games are tagged horror.
I dare say there is a certain imbalance and the apparant popularity of horror might be slightly skewed, maybe due to clickbait like youtube videos. Well. If it brings new players to the platform, all the better. Came for the horror, stayed for the indie games. Or similar.
But once you are on the platform, you might want to see a more diverse selection of games. There is, but you have to look for it and the "browse" button is too prominent compared to the other options.