Nobody wants a burger that’s one 1/8th pound patty and 3 inches worth of solid lettuce.
Had regulars when I worked fast food that would order the kid size burger with a fuckton of lettuce and tomato. Just way too much.
Pre-0.19 I assume you would need to be on an instance that is blocking them.
Post-0.19 you can block them as an instance, meaning “any posts from communities which are hosted on that instance are hidden”
So, the answer still varies depending on your goals for blocking.
For clarity:
I would just write the world in a way that is interesting to you, and add to it as players show interest. “Hey, I want to play a Tabaxi” -> “oh okay, let me think about what that means and I’ll get back to you.” This also gives you more latitude for using their ideas to inform the world. “I want to play a Tabaxi Wizard” -> “oh interesting, maybe there’s a clan of them that…”
You’ll be able to focus on what you care about, which will make the world more interesting, and allow players to incorporate things they care about if they wish, which will make it more fun for them too. Framing it in terms of “up for deletion” implies you need to answer everything about the world from the start, which is not only inefficient but an impossible standard. Just because you haven’t considered something doesn’t mean it can’t exist.