Does one need to balance input with textbook learning?

So I'm learning primarily via input. I do a lot of intensive immersion with Visual Novels and any unknown word or grammar point that I see, I do search up using either Yomitan or Google (mainly DoJG for grammar). I've already read Tae Kim and have memorised a decent amount of vocab before starting out so I already have a foundation.

I can't understand if I'm missing anything here (besides probably a lack of listening input but that's not my main concern) but I've been told by like two or three people at this point that input alone isn't enough and that I should be using textbooks because "my grammar and vocab count is too low for native content."

I was just wondering if this was an overall agreed-upon consensus that textbooks should be an absolute staple in one's routine, and if so, what benefit would they really provide? I find my setup rather complete but I'm asking this just to see if I am missing anything.