With many website hosting services, you develop (and even debug / test) a website offline, then upload it to the hosting service, using File Transfer Protocol. That's what FTP is - a network protocol for moving files from computer to computer. And a website is a bunch of files.
Blogger provides an online development and test environment. With Blogger, you create your entire website using Post Editor and accompanying utilities ("Settings", "Template Editor", etc). When you're done, your website is there, hosted in Google. No need for using FTP, to upload a website, after you created it.
Until last year, the term "FTP" referred to a procedure for hosting Blogger blogs outside the Google naming / server space. Last year, even that option ended.
The option of publishing a Blogger blog, to a non BlogSpot URL, as
www.mydomain.com/blogis over. Now, your only option is
blog.mydomain.comusing custom domain publishing.
You may be able to simulate specific addresses, such as "www.mydomain.com/blog", using properly constructed custom redirects.
Part of the procedures provided by Blogger, to help blog owners survive the process of migrating their FTP published blogs back to Blogger / Google hosting, included a feature called "Missing Files Host". This let the blog owners leave key portions of their Blogger blogs hosted on the remote (non Google) server, and publish only new content in their blogs, newly hosted by Blogger / Google.
It's possible that some blog owners, the lucky ones for whom The Migration went seamlessly, are ignoring it as a significant event - and are seeing it as a mere "bump in the road" of their Blogger life (and FTP Publishing was bumpy, for many). Some blog owners may continue to tweak their (non Google hosted) websites using utilities provided by the hosting service, and may be using their (formerly Blogger published, now non Google hosted) websites as static content.
Having ignored the migration, these Blogger blog owners may be confused about why their Blogger published new posts don't show up in their non Google hosted website.
Blogger blog owners who publish web content hosted on non Google servers may wish to think about migrating the remainder of their websites to Blogger / Google hosting. At least, some blog owners may reflect that we are approaching the one year anniversary of the end of FTP Publishing.