Fossil SCM vs Squarespace

While most other platforms allow either online blogging, or development offline and hosting on some other platform, fossil allows you to develop locally, host it locally, view it locally, and you can substitue locally with remote if you want to.
It's just one file. Fossil.

It is. It is also free as in libre, as in the license is similar (or equivilant) to BSD-2

Fossil doesn't depend on a specific language to be present on the target or development system. Just write, commit, and done.

Squarespace's WYSIWYG tools are intuitive and support drag & drop functionality allowing you to change existing layout or add an article quickly.

Squarespace templates offer an optimal viewing experience depending on the width of the browser window so they will work and look great both on desktop and mobile devices.

Squarspace allows complete creative control over how you want your website to look and function. It can be a complete website.

Squarspace offers detailed metrics, that can also easily be accessed from your phone via an iOS app.

Squarespace has a bunch of small nice-to-haves that make it a pleasure to use, like automatically getting a screengrab when adding a video so that the site doesn't load the whole video before the user has clicked on it, or a sign-up process that's sane among other things.

Squarespace offers a great selection of highly polished templates across a variety of categories and styles.

Squarespace promises to answer all question within an hour.