Chris Kavanaugh:
Our species got along fine for millenia with small lithic,bone and wood edges that didn't even possess tangs. A good knife makes things much easier, but it's not a panacea for every need.

Ah. That answers my question, I think. Any knife is better than no knife. While some tasks will be easier with a certain size and type of knife, any knife can be used for almost any task with some degree of success.

Thanks, Chris.