I had a related idea today, which would I think be an extension of or additional function for a “Formula Relation”. Basically have some formula functions to operate on page contents (blocks) in some way, not just Relations. So for example you could count how many blocks there were in a page, or count how many characters were in a certain type of block, or count how many checkbox blocks are in “unchecked” state. Something like: countif(page.contents,block.checkbox,0) in psuedo-Excel language. 
I am not sure how many other uses this might have, but I suspect it might be the kind of thing where many uses emerge once the functionality becomes available and all the creative alpha users get access to it. 
I hope that makes it worth adding!