Or maybe it's that comments: a) load fast b) are always text c) don't include ads or videos d) are somewhat uniformly formatted and relatively easy to parse e)

Or maybe it's that comments: a) load fast b) are always text c) don't include ads or videos d) are somewhat uniformly formatted and relatively easy to parse e) often include enough of a summary to make a quick decision about a link There are usually lots of valuable features contained in comments that are quick/easy to use.