Then you have to pay for a server to run the cron jobs which would be more expensive. You could run it from home, but then you need to manage uptime yourself.
A simple cron job doesn't require managing uptime. It just needs to run frequently enough and then upload the generated HTML to github. I'm sure he uses his laptop at least once a day. This is crazy!!!
I don't know about OP, but I know that I often don't use my (personal) laptop once a day. I think I went a month earlier this year where I only touched it twice, and that was to move it out of the way so I could write a letter at that desk. Setting up something like this that's so inexpensive is a reasonable selling point for hobby projects that fit the model AWS has been designed for.