Have you read the eponymous book by Cal Newport? That's where these tools being labeled for "deep work" are coming from. It's a great book, I'd highly recommend it. Overall though I don't think you necessarily need a tool for deep work, but it can help.
I have not read the book, but I am aware of it. That's why I think it is so similar to GTD: started as a book, became very popular with the tech community leading to a few tools being made for it, became a common sight on HN front page, (we have not gotten here yet with deep work) became clear it was not a silver bullet and lost its lustre, vanished from front page, some people still use it.
