I begged Leaf to implement a negative filter years ago, which I believe is where the unofficial workaround came from. At the time it was implied that such a feature was in the works but low priority. The site devs seemed bewildered as to why I was seeing so many visual novels in the listings, and I put it down to me filtering to see games that support Linux, which by virtue of things like RenPy meant that certain types of games would appear more frequently. Unfortunately a proper negative filtering system has never materialised, and certain ideological leanings are over-represented on the site, which somewhat reflects political and cultural trends in the wider tech scene, so the problem inevitably has only gotten worse.
I gave up on the site a few years ago, despite having believed it was a vital resource for indie devs early on. Just logged in for the first time in a long while, and 9 out of 10 games in the default listing for me were visual novels. I long for a new site that fills the void, but as you indicate, the problem is likely to be replicated on any similar site, especially with LLMs lowering both the bar for entry and the quality of output. *sigh*