Please answer these questions:
How do I exclude on Newgrounds? How do I exclude on Gamejolt?
You claimed it is possible. I want to know how.
And can you or anyone else describe in a use case how multiple tag exclusion would be actual useful. Please.
Because, well, I have access to tools and ways to implement client side full multiple tag exclusion. It takes a minute to set up, but it works. But I just see no benefit in it. Convince me, that I can find my favorite game only by using multiple tag exclusion. Or at least, much faster. And also convince me, that I will not miss my future favorite game by having accidentally used a tag exclusion.
I do see a tremendous benefit in ticking games off, so you do not see them again. Like described here https://itch.io/t/1018893/a-never-show-me-this-again-please-button And this will be heaps better than ignoring tags. The first pages of popular do not change fast. Ticking off games takes a minute and they stay ticked off and will not clutter your browsing.
That is what I use, and it is very effective. Tag exclusion is nice on paper, but it is of questionable use when you consider how the games are tagged. It is the developers that do it, and they have different opinons about tags. So they might not tag the unwanted tag, or have the unwanted tag, but the content does not qualify for the tag in your opinion.