They cut it up into bite-sized pieces? I really doubt that. Notice only people who worry about etiquette tend to do that, and I don't think etiquette existed when we were cutting things with rocks. Perhaps chunks were sliced off, but I can't help but laugh at the thought of a Stone Age man cutting his meat into little cubes.
As a further argument, notice how most people eat a drumstick? It comes naturally.
Uh, pretty much every day? I'm pretty sure that's what pre-humans did, too. They butchered, cooked, and cut it up. Dentition is irrelevant.
> it'd be ridiculously hard with stone tools.
They were kept razor sharp. It would not be hard.