I'm sure most people know how to do this with their own voice.
Talking and singing are two different things. I can't carry a tune worth my life. But its all about matching the voice with the character, anyone can voice act if their voice can fit the character. Some people are talented enough to use different dialects and tones and such and thats why their valued more. With regular NPCs who have no unique "speech" could be done by anyone.
Instead of having one guy voice the entire imperial legion or male orc population we could have had a better number of different voices with variety. Some people would do it for free really if given the chance.
Then again I care less for voice-acting and would just want a ton of dialogue to read and flesh out the world text only.
Sometimes its just lip syncing and a match of the wrong character and voice.
The lip syncing can be a visual aspect that was the (what ever you call the guy who does the visual facial expressions) fault aswell not knowing if that could fit the amount of words or the action.
I have come to the conclusion that you no idea what you're talking about. If you're going to have a discussion with someone, at least make sure you have a somewhat informed opinion beforehand. That's just respect for the people you're talking to/debating.
Voice acting is NOT just "talking". You can't pull a random person off the street and tell them to read some lines. Because then they just sound like a random person off the street who just read some lines. Voice overs require skill - the ability to properly convey the character's personality, the ability to imitate accents, the ability to express emotion, the ability to know where to properly apply inflection. Ever watch a voice over artist at work? Many use their hands, bodies and face to fully enter the character and deliver a great performance.
There's a reason gamesas doesn't nab a bunch of randoms and ask them to voice crap for free and instead employs local voice talent.
Believe me, dude, I've heard what it sounds like when you just get a regular joe to voice something. It's not pretty.