It would be much easier to block communities just from post three-dot menu. I man, there's really no benefit in visiting hentai tentacle porn community just to block them.
I requested the exact same thing yesterday and one developer said they'd do a PR but then deleted their comment. I get the impression the main dev doesn't want to due to the menu size.
Seems insane UX you have to visit the very thing you don't want to see to block it.
I really like the app but this is quite a big deal as the communities grow more and more and get weirder for me.