Often used for headings to demonstrate how versatile a product is.

For example if I am selling a cup the heading would be typed out:

Awesome cup! Perfect for coffee.

Then coffee gets backspaced out and it types tea.

Then that gets backspaced out and it types hot chocolate

Etc.

I use a typing library in my app to showcase the different things that might be typed into a text field. It draws attention to that particular spot in the app too.

A lot of programming tutorials on Youtube animate the typing in of text. That was the first (and only so far) use case that I thought of.