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.
There's a couple different reasons I ended up going with this solution for my site:
1) Most of the time, integrating social networks into your site means either a) using widgets that are hard to work into the main site flow or b) having a backend to pull and integrate social media posts for you. This solution essentially provides B without needing to maintain a backend.
2) When planning my site refactor, Github Pages appealed to me because of its speed and simplicity. This lets me preserve the site automation that would previously have required a CMS, and because the site is static and hosted by Github, I don't need to worry about bandwidth or usage limits.
I negotiated with my company to count my commuting time as work time, since my bus is not crowded and I can always get on my laptop and work with a hotspot. So in a sense you could say I make money while commuting because it counts towards my working hours. I also get part of my afternoon back :)
Your last paragraph, I feel, is focusing too much on the individual, direct contribution and ignoring the effect a person staying at home can have on their family. By taking care of their auxilliary needs and letting them focus on their core tasks (work, school, etc.), the increase in productivity of the family as a whole can exceed that of a direct individual's contribution. I think of it as a project manager for the family - they don't directly contribute to the development of a project, but they handle the overhead that would otherwise thrash their developers.
The email links definitely contain tokens - not only will they log you in but the articles they generate on the page will reflect the order of articles in the email you received, as opposed to the most recent articles on your feed.
This is already in place - by default macOS does not allow apps to be installed which do not include a signed Apple developer ID. The setting can be turned off in System Preferences.