I work in accessibility. I'm non binary and queer AF.

The particles are a problem for some sensory processing disorders that cannot tune out motion. This is why the prefer reduced motion attribute exists.

I appreciate that you and I probably agree that some people with anti-LGBTQ sentiments will pick on anything atypical about a website like this to claim some notional moral high ground to punch down, but in the case of the particles specifically there are disability accommodation reasons to consider them something toggleable.

(Though using reader mode is probably sufficient for those users, as the site is developed to support it well.)