I think we should explore this. I don't think this is about extra clicks... On tablets like desktop we expand sections by default but __allow___ them to be collapsible. It would be interesting to add some event logging to see how widely used that feature is on tablet.
It could thus also be useful for desktop and I wouldn't outright dismiss it without evidence to backup it's usefulness.
Like Eallan I find this feature useful on both mobile and desktop (I use mobile site as my desktop experience) for navigating around complex documents.
Eallan happy to combine brainpower and work out a sensible test to see if it is useful or not if you are.