Comment by troad
SSG != WordPress.
The value proposition of WordPress is that grandma can run her knitting blog. Not quite as straight forward to teach nana Markdown, jekyll, the command line, SFTP... It's true that anyone who can roll their website with a SSG doesn't need WP, but those people were never WP's core audience anyway.
Not entirely incorrect, but a lot of these SSGs are essentially content management systems (eg Publii). Only gripe I have so far is no online editor