Your initial comment was why do they need to exist, not just that you don’t need one. That’s great you like your setup and it works for you. olive_tips point was that they exist because other people like them and use them.

On a personal note, I have had my Kindle for years and don’t want or need a tablet. The battery still lasts weeks, and it is jail broken so I can easily transfer DRM free books from calibre. I have not held an iPad mini, but it is lighter than any other device I have held, and fits in my pocket.