If you visit any specific place daily, marking the things you have alreay seen works wonders. It's not just about visual novels that you do not want to see. Marking things you already know, was the motivation behind that script, and for that it works very efficient.
Imagine there would only be like half a page each visit visible, even if you scroll down 10 pages. You would even immediatly spot new games that were indexed later. The recurring games that appear there every month or two will be gone. The developers that release slop after slop will be gone (you can also mark developers). And if you run that script, you can also combine it with the other script that gives you a genre filter for the main genres.
But beware, on some days, half the games you see will be malware. That's how it was a year ago. I hope it got better.
Filter options from within the site's system sure would be nice. So would an ignore this button, as Steam has it.
But I have doubts that it will be implemented any time soon. The exclusion filter from years ago was never expanded, nor got a user interface. But it was not removed either. Maybe it will rank higher in the priority list, if enough people officially request the feature. There is a feedback button on the left and request feature is one of the options.