Yes. Especially if you have a lot of subscribers and make frequent posts. My D had a lifestyle/photography blog in HS with ~1,000 followers that she updated at least weekly. She listed it as an EC. I’m a graphic designer and artist and I personally thought it was worth putting down. She spent a lot of time and energy and creative talent on it.
Edit: if it’s a tumblr where you’re mainly reblogging stuff, then no.