Some people are puzzled by this: I am a writer, yet I still get books aimed at new writers like ones about plot, or creating characters, or on dialogue, and so on.
Some books just make sense; I’m self-publishing on the Kindle, so I’m reading many books about that. In a few months I won’t anymore.
The books about writing techniques also make some sense. First: any writer who thinks that there’s nothing more to learn is just fooling themselves. You can master what you’ve already learned, but there may be new approaches to elements that you’re not yet aware of.
This too will hopefully too be soon done however!