Is giving feedback compulsory?

[gaybay3]

Just wondering if it is compulsory as a buyer to give feedback to your sellers?  Just noticed someone bidding on an item I have for sale has not given any feedback to the various sellers.  Is it compulsory or just good manners?

[enigmabear]

Yep, just good manners

Very often though, folks just can't be bothered

(and many of those can't leave a red dot fast enough if there is any issue of any kind)