It used to be that if people "thumbed up" your comment, you earned points. Later, that seemed to stop working.
But there's another reason for doing it: For someone who doesn't have the time to read ALL the answers to another person's question (I consider that the original questioner is morally obligated to read all the answers that others have taken the time and energy to formulate, often with a great deal of thought and care), the NUMBER of "thumbs up" on a particular comment SHOULD indicate just how useful it is.
I have seen loads of EXCELLENT comments without a single "thumbs up" - even though the questioner has written "Thanks so much for your advice"!!!
Come on, People! This site should be used for mutual support. You shouldn't "thumbs up" every comment you read, but how much energy does it take to do so to a comment that you find REALLY useful???
p.s. The same goes for shared work: If I haven't got time to read 3 long pieces, it would be nice to be able to see at a glance just how well-received they've been by others on this site.
It would be even better if we were given the option: "Rate this comment from 0 to 9" and then the average + number of voters were visible to others. But we can't ask for the moon, can we?
CAN we?
What ELSE are we doing if we're trying to get our work published??? (Answer: We're asking for the moon AND the stars AND the love and respect of thousands of enchanted readers.)
Even without the "thumbs up", I have come to know that certain people on this site ALWAYS write comments that are useful and well thought-out (e.g. Lorraine Swoboda), and others are often good for a laugh and worth reading if only for that (e.g. Kate Baxter). New users are going to have to find their own favourites...