Eagles Over the Kennebec

They're one of the things that's easy to do badly. (TNH gives the example of an author writing that someone "hissed" a sentence that contained no sibilants.) I suspect this is part of why people are told to avoid them altogether. And yes, if overused they distract from the actual conversation and events. Sometimes it's relevant that a character yelled or whispered. If an entire dialogue goes "said, spoke, shouted, mentioned, whispered, confided...." with a different verb at each line, that's likely to distract the reader (at least this reader) from what is being said.