Similar on surface - with cron you can only do stuff in intervals (AFAIK), for example once a day or hour or minute. Here the script is being run every time something changes (update in file, new file added, file removed, etc). Every time Logseq updates something on hard drive in directory with your repo, changes are commited to git and pushed to github. Which means there is no way to loose data (and you will always have access to latest state of your notes on multiple devices).
You can work in desktop Logseq app, have your local copy for offline use, and still being able to work with your data in Logseq on mobile browsers. This is the only way to mix these things together.
Also it’s impossible to upload images and other files to your private repo with browser version of Logseq, they are uploading them to AWS, not to github, so this is another reason to keep files on hard drive - images and files can be stored in “assets” folder on your drive and on github, you have full control over all of your data 