Before there was a like button people gave you a rep comment if they liked your comment. This is why majority of the older members have rep bars that are enormous (the green squares below your name and above your pic). And newer members such as myself have small ones. But if you go to a persons page you can see their likes given and received and how many posts they have. I normally being a child who used to play Call Of Duty turn this into a Kill death ratio....
Now a days they have turned into the anonymous "tell me how much you dislike me survey". Thankfully I have only gotten one of these surveys honestly surprised I don't have more.
Sometimes when I find a comment to be 100% to my beliefs I will give a rep saying how much I like that comment and or the person.
Hope this helps.