There can be some reasons. Assume you have a site/blog hosted by a service provider like Wordpress, Medium, Github.io, Blogger, Tumblr or some other local provi

There can be some reasons. Assume you have a site/blog hosted by a service provider like Wordpress, Medium, Github.io, Blogger, Tumblr or some other local provider. It can be expected at least some of them don't support SSL certificates for custom domains.