You can start with the original example 4 comments above and try to understand how unergonomic the default way of learning/remembering hundreds of key combinations in vim is.
Then think about the basics: why some of the most frequently used commands w/b are located so inconveniently and far away from each other (and if you reconfigure them, how unergonomic the config language is where instead of reading a sensible name like 'move_prev_word_start' you can only reference 'b' that you'd never use since, well, you've changed it to something else!)
You don't need hundred of commands to use vim, have you at least finished vimtutor? Finish it in the way it proposes, then start it again and think on your own, what commands for more effective passing the problems from vimtutor might have been there as well.
Letters w and b may be located wherever they are located, if you can not touchtype vim is not for you for the same reason we do not learn how to run before we master how to walk.