Dialogue forms a fundamental part of fiction writing. It's how the characters talk to one another—or how they don't talk—that provides insight into what is going on within a scene and what the characters might think about it. It's through dialogue that we can get the actual thoughts of other characters, not just the POV character. So much story often revolves around the dialogue.
However, when writing dialogue, many writers still new to the craft will fall back into an excessive use of dialogue tags. I have written about this some years ago, in the post Billy said... Diana said... In that post, I spoke about how it's not just the use of the word said that causes the issue. It's the over-excessive use of dialogue tags in general that can disrupt the flow of a story.
There are many writers and editors out there who will argue that using the word said isn't a problem. Even Stephen King says this. They rightly argue that our brains are trained to overlook the word said and move on. If you shift to the other dialogue tags (e.g., cried, shouted, bellowed, hissed, growled), our eyes are drawn to them, and we notice them.
This is all true, but the publishing industry as a whole is shifting away from the printed form (and I'm including eBooks as a printed form for this discussion). Audio books are taking a hold, giving people the ability to check out the latest book from their favorite author while they're out walking the dog. Whatever is on that printed page is directly translated to audio form, and the two ARE NOT the same.
Punctuation has a direct impact on this, bringing into question within editors' circles about how rigid we need to be with the punctuation rules. Whereas issues like the he-said-she-said fest become so obvious when read aloud.