It's important to me. If I can't block a person or account, I'm not using the platform. Don't care if it's FB, X, IG or whatever. I don't want to see what I don't want to seen. For me, controlling my content matters.
blocking is very important. if i don't like you, or i don't want anything to do with you, i'll block you. its simple. If i think you are a hateful person, i don't want to see your stuff and i sure as heck don't want you to see my stuff, blocked.
I also sell a lot of stuff on Facebook Marketplace. there are scammers all over the place. they are easy to spot when they message you, blocked.
also, in lieu of blocking, if i am friends with someone and i don't want to see their day to day drama (usually the crazy political rhetoric) i can just unfollow you and i won't see any of your stuff show up on my feed. but if i want to i can just click on your profile. if one thing Facebook has, its options to limit your feed.
Apple and Google make blocking a requirement for social media apps in their app stores. Musk has fought them tooth and nail on it.