TUMBLR is a fandom space. AO3 is a fandom space.
TWITTER and TIKTOK are NOT.
A fandom space is for fans ONLY. Nobody famous will be on tumblr or AO3 unless to actively engage with it. Twt and tiktok also have a purpose for content other than fandom content. THATS the difference!!
I like using Flickr more then catalogs and magazines because it shows what people were actually wearing, and not just what a company is trying to sell off