It's so weird, it never even occurred to me to take my own photos for articles on here. Medium kind of steers us towards using Unsplash - you don't even have to leave the story editor to insert a picture.
I guess it's a bit similar to all the bland music you hear on YouTube videos too.
This has defintley made me think and I'm going to take my own photos from now on too! - I think I'll also change some of my existing ones. Thanks!