Did you hit the feedback button and select request feature and told Itch about how you need that feature?
Maybe you can specify a use case where having that feature would benefit me or everone. I previously asked in other threads, but no one bothered to answer me. Or name other game platforms that have this feature (except Steam).
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If you are comfortable and able to use browser extensions, I made a user side tool that can simulate multiple tag exclusion effect. It takes a few minutes to set up, depending on how many tags you want to exclude. Maybe you can test out your use case and give feedback how much better you found what you were looking for, by using it.
It is three tools. A button for the existing exclusion filter. Buttons to exclude all the genres, like visual novel. And the third can exclude projects and developers at the press of a key. So you would just exclude all the genres and one tag and what is left you would positivly search for the tag you want to exclude and just put everything on the ignore list by holding the key down for a while. The browse lists are sorted by popularity, so the first few hundred should be enough and it takes a second to add like 50+ games.
Anyway, the feature described here and here is better than tag exclusion (marking games as seen/uninterested). It is what I use. If you want to declutter the first pages of popular browse section, tag filtering is only of so much use. Also you probably will filter away games you would like, but the developer chose a tag that you would disagree about.