I’m sorry to say, but it really does not matter what other people think. It’s like me, who has never been at your house, and never planning to be, thinking that your house rules are weird, arbitrary and petty. I’m also weirded out that you didn’t let that or this person in your house.
in a federated system necessarily yes it kind of does regardless of if you think that's fair. we get shit for what we believe (and maintain) are extremely valid and straightforward reasons for defederating with a handful of not-malicious instances and that can impact who comes here and why. if you were to create an image of being--for lack of better wording--a messy bitch with a catty and overdramatic attitude (as many people seem to read this as being) your instance will gain that reputation, it will influence who your users are, and it can go so far as to be negatively reflected onto completely innocent users.
now, if the mastodon.art person doesn't care about that then they don't care, and i'm again not saying that i care either way--it's their website, they can do what they want--but the presumption that this is in a vacuum or absent consequences is silly. it's not!