@aparrish @dredmorbius It is perhaps apocryphal because I can't find any actual records to support the fact, but I would swear that the first time that Facebook implemented the Like button was in response to demands that people were getting too many identical comments for the post in the form of "I like this!" and "Good Job!" and "+1!" and similar.
The Like button was supposed to be a shorthand of this, in order to surface the "real comments"...