There may be instances where Nano does something quicker but search and replace would seem to be a perfect example of the opposite where Nano has taken a quick one line thing in vi and turned it into a multistep process for simplicity.
Nano is different from vi because it targets a different set of users. Many of them use the terminal infrequently, so you can't assume they'll ever build up the kind of muscle memory that makes vi so efficient. You can't even assume that they'll remember any commands, so the commands are displayed prominently at the bottom. There's a reason so many Ubuntu tutorials for beginners use nano instead of vi.