I shouldn't have said paredit - I thought it had become a general term (is there one?) Most of my experience is with Cursive's 'Structural Editing' (sounds general, but is it?) features, and that's what I had in mind.
I wouldn't give a newcomer emacs (or vi) but I would give them the concept of paredit. The problem with that is fundamentally the keyboard, and it's a problem for the more seasoned of us too. I would kill for a programmable numpad-sized keyboard with removable caps that can be labelled by design so I can have a physical button for the operations I perform most often. I know similar things can be achieved with midi pads, but they're far from perfect. Programmable, configurable keyboards were a thing when I was at school (around the tail of the BBC Micro era) - where did they go?
This is exactly what I was suggesting
Also, tree editors make implementing additional editor features. You don't get that benefit with emacs + paredit since the data structure is still a text string at the end of the day.