If I would type at 15 WPM, I would be MUCH less productive than I am today for sure.
The point of using Vim, is that you boost your keyboard interface to the maximum. Obviously, using Vim, means you touch-type. Also, you don't use the mouse. Basically, using Vim, is like having the brain hard-wired to the computer for every task, not only text edition. Everything you do goes through the keyboard, and you don't have to think about it. You scroll through text, search for it, edit it, open new files, etc.
For instance, most of the time I don't use any GUI for Git either. I do everything in the terminal, and only use the GUI for partial commit (ie. select which line to commit). I have dedicated aliases for getting history, etc.
Also, when learning Vim, you notice that many (Linux) tools have Vim shortcuts enabled. I discovered many of them by chance, out of the habits of using Vim shortcuts.
Except web browsing, which is a huge part of software engineering, and which is nearly impossible to do without the mouse because most websites cannot be reasonably navigated with shortcuts alone.
Some avid vim users will also use https://vimium.github.io/ in their browsers, so they can also browse using the keyboard and vim-like cursor movement commands.
Most of my operations on a web browser involve scrolling or swapping pages, which I typically do with a keyboard. Besides every browser has keyboard extensions that allow one to select links through keyboard press. Being a neovim user I like vimium on firefox. I also like to use text based browsers for a better browsing experience and less distraction when I am coding.
For what it's worth, I have no problem using the mouse, or the keyboard, but I hate having to switch between them all the time. The longer I can use one without having to switch to the other, the better. Editing text can't really be done without the keyboard, so for that activity the use of the mouse should be absolutely minimal.
The point of using Vim, is that you boost your keyboard interface to the maximum. Obviously, using Vim, means you touch-type. Also, you don't use the mouse. Basically, using Vim, is like having the brain hard-wired to the computer for every task, not only text edition. Everything you do goes through the keyboard, and you don't have to think about it. You scroll through text, search for it, edit it, open new files, etc.
For instance, most of the time I don't use any GUI for Git either. I do everything in the terminal, and only use the GUI for partial commit (ie. select which line to commit). I have dedicated aliases for getting history, etc.
Also, when learning Vim, you notice that many (Linux) tools have Vim shortcuts enabled. I discovered many of them by chance, out of the habits of using Vim shortcuts.