I assume this website is just using the branding of the old site, I don't imagine it's been reopened in any meaningful manner. So talking about the history of SlutHate would actually not be referring to this current site.
SlutHate was opened up after PUAHate was shut down (which was due to the Elliot Rodger mass shooting.) It's not actually known for much of anything besides being a stepping stone for the current Looksmaxxing sites, and of course for the vulgar name.
It's the S in the PSL scale though. (P)UAHate (S)lutHate (L)ookism, so it's deemed foundational in current Looksmaxxing/incel (mainly Incel) culture and so on, which is why it's mentioned a lot.