Why would programmers need a separate tool for programming practice? Isn't the act of programming itself the best form of typing practice? I don't see a market

Why would programmers need a separate tool for programming practice? Isn't the act of programming itself the best form of typing practice? I don't see a market fit for this for the stated purpose. Also, the UI when you make a mistake is confusing, I didn't realise I had to backspace and correct it. While that seems obvious in hindsight, I actually opened it in a different browser to make sure I wasn't just hitting some bug before reading the comments here and realising.