I write code all day. Git is awesome, and you can pry Vim from my cold dead hands. But Jekyll is fiddly and doesn't really match my preferred writing workflow.
Ghost workflow: Visit URL, mash password manager (occasionally), click "new post" and start writing. Change the title whenever I feel like it. A live preview of the post appears on the left, and I click publish when I'm done. Click a little button in the UI to view the finished post on my site.
Jekyll workflow: Open a terminal. Create a new file named with the current date and the post stub. Half the time I don't know what either of those are off the top of my head. Open Vim. Type out the post metadata block. Inevitably get something wrong. Type post. Tab to the terminal and start Jekyll's server. Navigate to local server URL in browser. Alt tab back and forth between browser and editor, hitting F5 every time I want a new preview. Rename file with new stub (optional). Git add, commit, and push. Navigate to my public site in browser to make sure everything came out OK. Mash F5 a few times because Github Sites hasn't compiled it yet. Delete the "We compiled your site!" email from my inbox.
Note that Ghost requires much less prep; the majority of my time in Ghost is just editing my post's text. Jekyll has a larger lead in time to editing, and while editing I have to switch back and forth between my editor and the browser for a preview. Jekyll requires more effort doing busywork that isn't writing. I found my output dropped way off after I switched from Wordpress because the barrier to starting a post was higher.