(I started a separate account for my Disneybounds and cosplays and general nerdy stuff because I didn't want to explain myself to my cousin in Japan, who had started following me on Instagram.
I *could* have, and maybe should have, set my Disneybound/cosplay account to private, but sometimes I get tagged in group photos, and also I personally find it convenient when people I encounter at meet-ups have public Instagram accounts so I can be all "oh yeah, that's where I know that person from" or "that person seemed nice at the lightsaber meet-up, I'm glad to see via their stories that we have similar beliefs and values".)