"Alexa top domain" directories?

I've been researching my competitors from the adult niche and most of them are listed in these "Alexa top domain" lists that contain tons of links on a single page. I'm sure if you're working with the adult niches and checked your competitors at least once you saw these websites that have random domain names and share the exact same design. The one I checked right now is spammy as hell with the 89% Moz spam score. But they're still considered the most valuable links according to Semrush, and even the worst literal 1-month-old websites with the nonexistent on-page SEO and tons of ads are ranking on the last pages of Google for my focus keyword (10 mil. volume!), having the backlink profile that only contains the links from these directories, while I don't even rank for them at all. The button to buy 30 backlinks from these directories redirects the user to another domain that is the same in every "directory" and offers to buy them from $15 to $30 per 30 links.

Thoughts? They're unbelievably spammy, but they work, how that's possible? They sure should be a big no for any website that doesn't want to get penalized, shouldn't they?

I don't know the answer but every single dropped domain I look at has these backlinks. Which might mean that the ones that bought them that are still alive are the exception, and rank for some other reason not because of those links.

ive noticed the high ranking trend among sites having these alexa spam directory lists links too and i cant comprehend it