In this day and age, the iPhone is probably the only computer that some only own. People can create posts and articles on their iPhone for their blog or website, or even noting down key points for a speech. That would mean lots of typing involved.
If you belong to another group of people that uses these devices for connecting and communicating with people in your social circle, that would mean lots of typing of messages and replies too.
Although there is auto-correction however some words like a person’s name or a name of a place might not get corrected. We may sometimes misspell words and in the past, sometimes the only way is to delete the letters at the back though the mistake is at the start of the word or highlight the word and deleting them.
With 3D Touch Trackpad, you can now move the cursor to the exact location of the letter in a word, backspace and type the word. This does not occur only in words but also in sentences. You can 3D Touch from any move around the sentence or paragraph and even get into the exact letter of the word in a paragraph or sentence.