I think the point was more about mitigating the risk of being locked in to a platform with bespoke authoring tools. GitHub and Cloudflare are very convenient with their generous free services, but if you had to a hugo blog could still be hosted on any web server in the world.
> GitHub and Cloudflare can do these things at any moment
I hosted mine in AWS S3 with CloudFront for Https and custom domain. Using Hugo too. I wrote Cloudformation template for whole setup [0], just create the CFN stack using template in AWS. Then copy public html to S3 using "aws s3 sync" and done!
Those risks still exist. GitHub and Cloudflare can do these things at any moment.