I wonder whether the lack of a "like/favorite" button in Ello might be a good thing. It kinds of forces you to actually say something if you want to interact with someone, instead of just passively registering that you enjoyed or agreed with them.
On the other hand perhaps it will mainly cause people to interact less. If the level of interest you have with a post is not enough to justify thinking of a response, your reaction to it will simply go unregistered. So the "like" button does provide at least some utility.
I was thinking about what it would be like if real life social interactions had something similar to the "like" button. What if we could simply click a like button next to our friends' head when they said something you that you found agreeable. How would that change the way we communicated?
Then I realized we do have something like that. It's called a smile.