Reason 1 isn't accurate. You can simply copy-paste or drag and drop images into the editor on Steemit.

In general though, I don't find an advantage using either interface. They both have problems. I actually find the navigation on Busy to be lousy, which is why I've stayed on Steemit. Both interfaces need some serious design work and functionality/feature improvements. It's sad that there hasn't been more/better focus on that. Still waiting for that slick social media interface/app. I hope it comes soon.