I have been using WordPress for my personal blog and such task is trivial in WordPress with built-in sharing feature. What's more you can have control over the source code when you host it on your own VPS. The free WordPress hosting by wordpress.com has the same functionality built-in.
What are some of the advantages of using this workflow involving multiple services/tools? I feel that this is too many dependencies to accompany a simple task.
The only step in that chain that can take your blog offline for visitors is GitHub pages. The cool thing about static sites is they're really easy to replicate to a second provider. Or a 3rd, 4th, nth...
I could be wrong, but I believe WordPress' sharing features are built to share your WordPress posts out to other social networks - this tool is made to do the opposite, to take your posts from other forms of social media and import them as posts on your blog. I don't believe WordPress has that native capability - although it's worth noting that IFTTT natively supports posting to WordPress and other social networks as an action. Previously, my site was on Tumblr and I used IFTTT's Tumblr actions in a similar manner.
In my opinion, the primary advantage Github Pages has over a CMS like Wordpress is simplicity and lack of cruft. WordPress is an extremely powerful tool, but 95% of blogs, mine included, don't need the features that WP provides - and more importantly, the added code and serving overhead that comes with it.
When I've done WordPress development in the past, a lot of customization can be done on the theme level but sometimes you need to adjust the model around which a page is served and it can become confusing and complex with WP's expansive codebase. With Jekyll, it's easy to see every file and how those files combine to create my site pages. It's also easy to serve locally and I can rest assured that Github will build my site in the same manner as it's being built locally.
Finally, I would assert that I have much finer control over my source using Github Pages compared to WordPress - my site, in its native form, is literally a repository which I can move and rebuild on any number of platforms without any backend configuration. And that same repository is automatically open-sourced and built on Github without my having to maintain a build system. I never have to worry about migrating a database, I never have to worry about plugin updates breaking my page, and I never need to worry about PHP vulnerabilities compromising my data. When I look at Github Pages, I feel like GH really managed to abide by KISS principles, saying "what is the MVP for a blogging platform" and providing that in a clean & performant manner.
What are some of the advantages of using this workflow involving multiple services/tools? I feel that this is too many dependencies to accompany a simple task.