There are plenty of examples in other frameworks, e.g. sometimes view helpers in Rails output HTML. In certain situations it helps you write much cleaner code and it's easier to make more complex view components. Rails form helpers output HTML.

http://apidock.com/rails/ActionView/Helpers/TextHelper/conca...

http://thepugautomatic.com/2013/06/helpers/

http://guides.rubyonrails.org/form_helpers.html

https://github.com/rails/rails/blob/dd7af2c413a06ea44e50abf0...