Yeah, I actually think that diagram and "git-flow" has caused a lot of harm. It shows a complete misunderstanding of both continuous integration and what tags are for. I've successfully purged git-flow and dragged developers, kicking and screaming, to a simple master branch, tags and maintenance branch model a few times now.
When I first got started programming, the "git flow" method was the one that popped up and was referred to most when I googled how does git work. And so I thought that git flow was the canonical way to use git.
I tried adhering to it at my first job but I guess I didn't understand git flow well enough because people just thought I was making random branches for fun.